When we see records being broken and unprecedented events such as this, the onus is on those who deny any connection to climate change to prove their case. Global warming has fundamentally altered the background conditions that give rise to all weather. In the strictest sense, all weather is now connected to climate change. Kevin Trenberth
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“We have a new normal” thanks to climate change, explains leading reinsurer.
by Joe Romm, Climate Progress, January 4, 2018
HURRICANE HARVEY IMPACTS. CREDIT: GETTY IMAGES
It turns out 2017 was a uniquely disastrous year in more ways than one, evidenced by German reinsurer Munich Re’s recently released review of the year’s global catastrophes.
Led by massive, climate change-fueled hurricanes Harvey, Irma, and Maria, 2017’s natural disasters will cost insurers a record $135 billion. Adding in uninsured losses brings the total global damages to $330 billion, which is second only to 2011.
“We have a new normal,” Munich Re’s Ernst Rauch told Reuters. Rauch, who runs the group tracking climate change risks, pointed out that “2017 was not an outlier” in having more than $100 billion in insured losses (see chart below). “We must have on our radar the trend of new magnitudes,” Rauch said.
The big reinsurers like Munich Re make their money by insuring the companies that directly insure your property. Those smaller companies are often required by law to buy reinsurance because they lack the capital resources to pay out if there is a major disaster, like superstorm Harvey for instance.
Since the reinsurers must pay out billions and billions of dollars for such mega-disasters, they have a unique incentive to understand and predict trends in mega-disasters. That’s why companies like Munich Re and Swiss Re have been at the forefront of warning businesses and the public about the rise in extreme weather events due to climate change.
Indeed, back in September 2010, another year of stunning warming-driven extreme weather events, Munich Re issued a release noting it had analyzed its catastrophe database, “the most comprehensive of its kind in the world,” and concluded, “the only plausible explanation for the rise in weather-related catastrophes is climate change.”
Then in October 2012, the company released a massive 274-page report, “Severe weather in North America,” analyzing weather catastrophes and related losses since 1980 to understand trends and their causes, including man-made climate change.
Munich Re found that the number of weather-related loss disasters has been rising much faster in North America than anywhere else, and concluded, “Climate-driven changes are already evident over the last few decades for severe thunderstorms, for heavy precipitation and flash flooding, for hurricane activity, and for heatwave, drought and wildfire dynamics in parts of North America.”
Prof. Peter Höppe, who heads Munich Re’s Geo Risks Research unit, said at the time, “In all likelihood, we have to regard this finding as an initial climate-change footprint in our U.S. loss data from the last four decades.”
And last April, Munich Re published an article on “rapid attribution,” which explained that we can now rapidly determine how much intensity or frequency of some extreme weather events is affected by man-made climate change. Learning that, for instance, climate change has sharply increased the chances of individual extreme rain and flooding events – such as devastating August 2016 deluge and flooding of Baton Rouge, Louisiana – allows communities to do better planning and Munich Re to do better risk management.
The latest annual report amplifies the message that humans are changing the climate, boosting the intensity and frequency of extreme weather events, and that the longer we dawdle, the higher the costs we will incur. The only question is, is anyone listening?
The land is warming twice as fast as the oceans … too bad we live on the land
by Joe Romm, Climate Progress, August 22, 2017
ANNUAL (THIN LINES) AND FIVE-YEAR LOWESS SMOOTH (THICK LINES) FOR THE TEMPERATURE ANOMALIES AVERAGED OVER THE EARTH’S LAND AREA AND SEA SURFACE TEMPERATURE ANOMALIES. CREDIT: NASA
Global temperatures are rising faster on the land, where we live, than the oceans, where we don’t, NASA charts reveal. Since scientists have long predicted this trend and say it will continue, it’s worth a closer look.
Let’s start with the long-term global warming trend. According to NOAA, “Since 1880, surface temperature has risen at an average pace of 0.13 °F (0.07 °C) every 10 years, for a net warming of 1.71 °F (0.95 °C).”
But the warming is not evenly distributed: “Over this 136-year period, average temperature over land areas has warmed faster than ocean temperatures: 0.18 °F (0.10 °C) per decade compared to 0.11 °F (0.06 °C) per decade.” So over the entire record, the land is warming nearly 70 percent faster than the oceans.
But the warming is also speeding up. Over the last 45 years, surface temperature has been rising at an average rate of around 0.3 °F per decade — more than double the rate over the whole 135-year period. This speed up was also predicted. After all, emissions of CO2, the most important heat-trapping greenhouse gas, have increased by a factor of six since 1950 — and the rise of overall CO2 levels has sped up.
The disparity between the rate of land and ocean warming has also gotten bigger. NASA Goddard Institute for Space Studies (GISS) recently posted some charts that show just how much faster it has been warming in recent decades — and how much the disparity has grown.
In the past six decades, land temperatures have risen about 2.3 °F, a warming rate of nearly 0.4 °F a decade, as the top chart shows. That’s nearly double the temperature rise of the ocean, which is 1.25 °F per decade. Moreover, in the past 30 years, the rate of warming appears to have sped up even more, with land temperatures rising more than 0.6 °F a decade. That’s now a bit more than double the ocean warming.
But the key point, of course is that we live on the land. So when you see a rate of global warming quoted, remember, the rate of warming where we live is much higher — and growing fast.
Finally, you may be wondering why temperatures over the land are warming so much faster than temperatures over the ocean. Part of the reason is that the heat capacity of the ocean is so much greater than that of the land so its initial temperature response to warming is slower. As one explainer put it, “Think of the hot sand and cool water at the beach in the summer.” This is also why the ocean stores more than 90% of all of the excess heat from global warming.
Part of the reason the ocean warms more slowly is that much of the heating of the ocean goes into evaporation. But the land, particularly the drier parts of the planet, don’t have much moisture to evaporate—so much more of the global warming goes directly into temperature rise. For those technically minded readers who want a fuller explanation, start with this2009 study,“Understanding Land–Sea Warming Contrast in Response to Increasing Greenhouse Gases.” Then try this2013 study.
By exiting the Paris climate deal, President Donald Trump has made this future for South Florida and “Miami Island” all but unstoppable. CREDIT: Climate Central. by Joe Romm, Climate Progress, June 1, 2017 President Donald Trump announced Thursday that the United States will withdraw from the Paris climate accord. In doing so, he has made the worst-case impacts of climate change on America vastly more likely.
In a speech from the White House Rose Garden filled with thorny lies and misleading statements, one pricks the most: Trump claimed that the Paris climate deal would only reduce future warming in 2100 by a mere 0.2 °C. White House talking points further assert that “according to researchers at MIT, if all member nations met their obligations, the impact on the climate would be negligible… less than 0.2 degrees Celsius in 2100.”
The Director of MIT’s System Dynamics Group, John Sterman, and his partner at Climate Interactive, Andrew Jones, quickly emailed ThinkProgress to explain, “We are not these researchers and this is not our finding.”
They point out that “our business as usual, reference scenario leads to expected warming by 2100 of 4.2 °C. Full implementation of current Paris pledges plus all announced mid-century strategies would reduce expected warming by 2100 to 3.3 °C, a difference of 0.9 °C [1.6 °F].”
The 0.2 °C estimate used by Trump may be from another MIT group; the Joint Program on the Science and Policy of Global Change did have such an estimate in early 2015, before all of the Paris pledges were in. But, their post-Paris 2016 analysis also concluded the impact of the full pledges was closer to 1 °C.
In their analysis, Sterman and Jones “take all nations at their word that they will fully meet their national commitments. If nations increase their ambition and set future pledges, as is outlined in the agreement, then the positive impact would be even larger.”
This point is key. The Paris commitments not only help the globe avoid the worst-case scenario for total warming and related climate impacts, they keep the best-case scenario open. Indeed, the Paris pledges buy us another decade close to the 2 °C (3.6 °F) path.
Keeping the option of beating the 2 °C target — which is widely seen by scientists as the point at which climate impacts start to become dangerously unmanageable by humans — is a key objective of the Paris deal.
Earth has already warmed 1 °C from carbon pollution, and the latest science says the globe is already approaching many tipping points. Among the most imminent and consequential for America and the world involves sea level rise.
The disintegration of the Greenland and Antarctic ice sheets is speeding up, providing more evidence we are headed for the worst-case scenario of sea level rise — three to six feet (or more) by 2100 — unless total warming is limited to “well below 2 °C,” as Paris envisions.
And Trump is not merely working to thwart both domestic and global climate action, he slashes funding for coastal adaptation in his latest budget.
But this is not just South Florida’s problem. The entire country is facing a trillion-dollar bubble in coastal property values.
So when will the bubble burst? In short, when sellers outnumber buyers, and banks become reluctant to write 30-year mortgages for doomed property, and insurance rates soar, then the coastal property bubble will slow, peak, and crash. The process speeds up when a large fraction of the financial community — mortgage bankers and opinion-makers, along with a smaller but substantial fraction of the public — realize that it is too late to stop catastrophic sea level rise.
With Trump withdrawing the U.S. from the Paris agreement, that moment would appear to be at hand, which leaves one final question: Who will be the smart money that sells their coastal property early — and who will be the other kind of money?
Oxygen levels ‘falling 2 to 3 times faster than predicted’ in our warming oceans, study finds
Much of the ocean is seeing sharp drops in oxygen levels (purple). CREDIT: Georgia Tech.
by Joe Romm, Climate Progress, May 8, 2017
Depletion of dissolved oxygen in our oceans, which can cause dead zones, is occurring much faster than expected, a new study finds.
And by combining oxygen loss with ever-worsening ocean warming and acidification, humans are re-creating the conditions that led to the worst-ever extinction, which killed over 90% of marine life 252 million years ago.
Researchers at Georgia Institute of Technology reviewed ocean data going back to 1958 and “found that oxygen levels started dropping in the 1980s as ocean temperatures began to climb.”
Scientists have long predicted that as carbon pollution warms the globe, the amount of oxygen in our oceans would drop, since warmer water can’t hold as much dissolved gas as colder water. And, Georgia Tech researchers point out, falling oxygen levels have recently led to more frequent low-oxygen events that “killed or displaced populations of fish, crabs and many other organisms.”
But what is especially worrisome about this new research is how quickly it is happening. “The trend of oxygen falling is about two to three times faster than what we predicted from the decrease of solubility associated with the ocean warming,” said lead researcher Prof. Taka Ito. “This is most likely due to the changes in ocean circulation and mixing associated with the heating of the near-surface waters and melting of polar ice.”
Global warming drives ocean stratification — the separation of the ocean into relatively distinct layers. This in turn speeds up oxygen loss, as explained in this 2015 video.
A 2011 study, “Rapid expansion of oceanic anoxia immediately before the end-Permian mass extinction,” found that rapid and widespread anoxia (absence of oxygen) preceded “the largest mass extinction in Earth history, with the demise of an estimated 90 percent of all marine species.”
As National Geographic reported in 2015, we’re already starting to see the impacts of anoxia. “The waters of the Pacific Northwest, starting in 2002, intermittently have gotten so low in oxygen that at times they’ve smothered sea cucumbers, sea stars, anemones, and Dungeness crabs,” the magazine reported.
Finally, a 2015 study foundthere is no techno-fix to prevent a catastrophic collapse of ocean life for centuries if not millennia if we continue current CO2 emissions trends through 2050.
If we don’t start slashing carbon pollution, then, as co-author John Schellnhuber put it, “we will not be able to preserve ocean life as we know it.”
Last month was the hottest March on record, according to newly-released satellite data. And it followed the hottest February on record.
The Arctic was literally off-the-charts warm last month, as we’ll see. It’s no surprise, then, that Arctic sea ice set a record for the lowest maximum extent.
First, the University of Alabama at Huntsville (UAH) data shows that in March the lower troposphere (the lowest part of the atmosphere) was a remarkable 1.3 °F (0.73 °C) above the historical (1981-2010) average, a baseline that is already some 0.8 °F (0.45 °C) hotter than pre-industrial levels.
The lower tropospheric temperature (LT) anomaly, via UAH scientist Roy Spencer.
Higher highs and higher lows — the warming trend is quite clear in the satellite data. As the UAH’s Roy Spencer and John Christy — both leading deniers — have reported, the UAH data shows a “global climate trend since Nov. 16, 1978 [of] +0.12 °C [0.22 °F] per decade.”
But wait, how is it that Ted Cruz and other climate science deniers keep claiming there hasn’t been any warming in the satellite record since 1998? The short answer is they’ve been ignoring all of the reliable sources that show warming, but have focused on the one satellite record that even Spencer and Christy knew was in error. Now that this error has been corrected in the peer-reviewed literature, as we reported, there aren’t any more datasets that don’t show warming.
“Record-Shattering February Warmth Bakes Alaska, Arctic 18 °F Above Normal,” was the Climate Progress story last month when NASA released its February temperature data. How warm was the Arctic in March? Off the charts.
Look at what the heat did: It kept Arctic sea ice growth almost flat for over a month during a time when sea ice extent normally soars to its annual maximum. The result, as the National Snow and Ice Data Center (NSIDC) reported last week, was the lowest winter maximum on record.
“I’ve never seen such a warm, crazy winter in the Arctic,” reported NSIDC director Mark Serreze. “The heat was relentless.”
The NSIDC has a metric for how warm (or cold) the Arctic has been called “freezing degree days” (FDDs). Their website explains:
The relationship between thermodynamics and sea ice thickness can be thought of most simply in terms of freezing degree days (FDD), which is essentially a measure of how cold it has been for how long. The cumulative FDD is simply daily degrees below freezing summed over the total number of days the temperature was below freezing.
NSIDC scientist Andrew Slater has an amazing chart on his website of freezing degree days in 2016 compared to other years at 80° N latitude:
In the Arctic, 2016 (bottom red line) has been anomalously warm.
“This year’s trend line is not only way outside of the percentile zones,” Neven Acropolis notes at his must-read Arctic sea ice blog, “it’s falling off the chart.” This unusual warmth is a key reason Arctic sea ice extent just saw its lowest maximum on record.
It bears repeating that recent research finds that rapid Arctic warming, driven in part by sea ice loss, is already worsening extreme weather. Also, the permafrost contains twice as much carbon as the atmosphere, and as it defrosts, it releases that carbon in the form of either CO2 or an even more potent heat-trapping greenhouse gas, methane (CH4). Thus as Arctic warming speeds up, it boosts global greenhouse gas levels, which leads to even more warming of the Arctic and so on.
That’s why we must pay attention to what happens in the Arctic — and do everything we can to stop global warming ASAP.
James Hansen and 18 leading climate experts have published a peer-reviewed version of their 2015 discussion paper on the dangers posed by unrestricted carbon pollution. The study adds to the growing body of evidence that the current global target or defense line embraced by the world — 2 °C (3.6 °F) total global warming — “could be dangerous” to humanity.
That 2 °C warming should be avoided at all costs is not news to people who pay attention to climate science, though it may be news to people who only follow the popular media. The warning is, after all, very similar to the one found in an embarrassingly under-reported report last year from 70 leading climate experts, who had been asked by the world’s leading nations to review the adequacy of the 2 °C target.
Specifically, the new Hansen et al. study — titled “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous” — warns that even stabilizing at 2 °C warming might well lead to devastating glacial melt, multimeter sea level rise and other related catastrophic impacts. The study is significant not just because it is peer-reviewed, but because the collective knowledge about climate science in general and glaciology in particular among the co-authors is quite impressive.
Besides sea level rise, rapid glacial ice melt has many potentially disastrous consequences, including a slowdown and eventual shutdown of the key North Atlantic Ocean circulation and, relatedly, an increase in super-extreme weather. Indeed, that slowdown appears to have begun, and, equally worrisome, it appears to be supercharging both precipitation, storm surge, and superstorms along the U.S. East Coast (like Sandy and Jonas), as explained here.
It must be noted, however, that the title of the peer-reviewed paper is decidedly weaker than the discussion paper’s “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming is highly dangerous.” The switch to “could be dangerous” is reminiscent of the switch (in the opposite direction) from the inaugural 1965 warning required for cigarette packages, “Caution: Cigarette Smoking May Be Hazardous to Your Health” to the 1969 required label “Warning: The Surgeon General Has Determined that Cigarette Smoking Is Dangerous to Your Health.”
And yes I’m using the analogy to suggest readers should not be sanguine about the risks we face at 2 °C warning. Based on both observations and analysis, the science is clearly moving in the direction that 2 °C warming is not “safe” for humanity. But as Hansen himself acknowledged Monday on the press call, the record we now have of accelerating ice loss in both Greenland and West Antarctica is “too short to infer accurately” whether the current exponential trend will continue through the rest of the century.
Hansen himself explains the paper’s key conclusions and the science underlying them in a new video:
The fact that 2 °C total warming is extremely likely to lock us in to sea level rise of 10 feet or more has been obvious for a while now. The National Science Foundation (NSF) itself issued a news release back in 2012 with the large-type headline, “Global Sea Level Likely to Rise as Much as 70 Feet in Future Generations.” The lead author explained, “The natural state of the Earth with present carbon dioxide levels is one with sea levels about 70 feet higher than now.” Heck, a 2009 paper in Science found the same thing.
What has changed is our understanding of just how fast sea levels could rise. In 2014 and 2015, a number of major studies revealed that large parts of the Antarctic and Greenland ice sheets are unstable and headed toward irreversible collapse — and some parts may have already passed the point of no return. Another 2015 study found that global sea level rise since 1990 has been speeding up even faster than we knew.
The key question is how fast sea levels can rise this century and beyond. In my piece last year on Hansen’s discussion draft, I examined the reasons the Intergovernmental Panel on Climate Change (IPCC) and scientific community have historically low-balled the plausible worst-case for possible sea level rise by 2100. I won’t repeat that all here.
The crux of the Hansen et al. forecast can be found in this chart on ice loss from the world’s biggest ice sheet:
Antarctic ice mass change from GRACE satallite data (red) and surface mass balance method (MBM, blue). From Hansen et al.
Hansen et al. ask the question: if the ice loss continues growing exponentially how much ice loss (and hence how much sea level rise) will there be by century’s end? If, for instance, the ice loss rate doubles every 10 years for the rest of the century (light green), then we would see multi-meter sea level rise before 2100? On the other hand, it is pretty clear just from looking at the chart that there isn’t enough data to make a certain projection for the next eight decades.
The authors write, “our conclusions suggest that a target of limiting global warming to 2 °C … does not provide safety.” On the one hand, they note, “we cannot be certain that multi-meter sea level rise will occur if we allow global warming of 2 °C.” But, on the other hand, they point out:
There is a possibility, a real danger, that we will hand young people and future generations a climate system that is practically out of their control. We conclude that the message our climate science delivers to society, policymakers, and the public alike is this: we have a global emergency. Fossil fuel CO2 emissions should be reduced as rapidly as practical.
I have talked to many climate scientists who quibble with specific elements of this paper, in particular whether the kind of continued acceleration of ice sheet loss is physically plausible. But I don’t find any who disagree with the bold-faced conclusions.
Since there are a growing number of experts who consider that 10 feet of sea level rise this century is a possibility, it would be unwise to ignore the warning. That said, on our current emissions path we already appear to be headed toward the ballpark of 4-6 feet of sea level rise in 2100 — with seas rising up to one foot per decade after that. That should be more than enough of a “beyond adaptation” catastrophe to warrant strong action ASAP.
The world needs to understand the plausible worst-case scenario for climate change by 2100 and beyond — something that the media and the IPCC have failed to deliver. And the world needs to understand the “business as usual” set of multiple catastrophic dangers of 4 °C if we don’t reverse course now. And the world needs to understand the dangers of even 2 °C warming.
So kudos to all of these scientists for ringing the alarm bell: James Hansen, Makiko Sato, Paul Hearty, Reto Ruedy, Maxwell Kelley, Valerie Masson-Delmotte, Gary Russell, George Tselioudis, Junji Cao, Eric Rignot, Isabella Velicogna, Blair Tormey, Bailey Donovan, Evgeniya Kandiano, Karina von Schuckmann, Pushker Kharecha, Allegra N. Legrande, Michael Bauer, and Kwok-Wai Lo.
December 2015 through February 2016 was the hottest meteorological winter ever by far, topping the previous record by a jaw-dropping half a degree Fahrenheit. The National Oceanic and Atmospheric Administration (NOAA) reports that this winter was a remarkable 2.03 °F above the 20th century average.
This extreme warmth — caused primarily by the accelerating human-caused global warming trend (with a boost from El Niño) — is a key reason a number of countries have already “set records for the all-time most expensive weather-related disaster in their nations’ history” this year, as meteorologist Jeff Masters has explained.
We already knew from NASA surface temperature data and from the satellite data that this was the hottest February on record by far. Indeed, every database confirms that February was the most extreme deviation from “normal” temperatures ever recorded for any month!
NOAA’s latest monthly “State of the Climate” report reveals just how hot temperatures over land were, as recorded by the Global Historical Climatology Network (GHCN), an “integrated database of climate summaries from land surface stations across the globe.” NOAA reports that “a total of 115 individual GHCN stations from 38 countries across all inhabited continents and several island nations set new February high temperature records.”
CREDIT: NOAA
The Earth’s landmasses were so hot in February that NOAA reports these stunning facts:
The February globally-averaged land surface temperature was 4.16 °F (2.31 °C) above the 20th century average. This was the highest for February in the 1880–2016 record, surpassing the previous records set in 1998 and 2015 by 1.13 °F (0.63 °C).
Yes, last month beat the all time record for hottest February over land by a staggering 1.13 °F.
Because of such scorching heat in February and indeed all winter, it’s no surprise that a number of countries saw record-setting weather-related natural disasters.
“According to the February 2016 Catastrophe Report from insurance broker Aon Benfield, three nations suffered extreme weather disasters in February 2016 that cost at least 4% of their GDP — roughly the equivalent of what in the U.S. would be five simultaneous Hurricane Katrinas,” Jeff Masters and and Bob Henson explain at Weather Underground:
The three unlucky nations that suffered their most expensive weather-related natural disasters ever are Vietnam, Zimbabwe, and Fiji:
“Vietnam has suffered $6.7 billion in damage from its 2016 drought, which has hit farmers especially hard in the crucial southern Mekong Delta. This cost is approximately 4% of Vietnam’s GDP, and beats the $785 million cost (2009 USD) of Typhoon Ketsana of September 28, 2009, for most expensive disaster in their history.”
“Zimbabwe has suffered $1.6 billion in damage from its 2016 drought [with more than a quarter of the population facing food shortages]. This is approximately 12% of their GDP, and beats the $200 million cost (2003 USD) of a February 2003 flood for most expensive disaster in their history.”
“Fiji suffered $470 million in damage from Category 5 Cyclone Winston’s impact in February [peak strength 185 mph winds]. This is approximately 10% of their GDP. The previous costliest disaster in Fiji was Tropical Cyclone Kina in January 1993, at $182 million (2016 USD) in damage.”
Given that this month looks to be headed toward the hottest March on record by far — and given that it would surprise no one if this were the hottest spring on record by far — much more such extreme weather disasters are yet to come.
It’s worth remembering, though, that however bad it gets this year, if we don’t continue to sharply reverse global emissions trends, then our current extreme weather will simply be the norm by mid-century — and it will be considered mild by century’s end.
CREDIT: ROY SPENCER, UNIVERSITY OF ALABAMA AT HUNTSVILLE
by Joe Romm, Climate Progress, March 2, 2016
February smashed monthly global temperature records, according to the satellite data analyzed by the University of Alabama at Huntsville (UAH). At the same time, a brand new study concludes that miscalculations explain why the Remote Sensing Systems (RSS) satellite temperature dataset had appeared to show a relatively slow rate of global warming.
So Ted Cruz and his fellow climate science deniers need a new meme to replace their “satellites find no warming since 1998” talking point, which replaced the “there’s been no warming since 1998” talking point after that one fell apart when 2014 became the hottest year on record — and again when 2015 blew away the 2014 record.
Let’s start with the UAH data, which show a stunning 1.5 °F (0.83 °C) warming in February 2016 compared to the historical (1981-2010) average for the lower troposphere (the lowest part of the atmosphere):
The lower tropospheric temperature (LT) anomaly, via UAH scientist Roy Spencer.
How amazing is this temperature jump? First off, remember that the 1981-2010 baseline used by the UAH is itself some 0.8 °F (0.45 °C) hotter than pre-industrial levels — so you can add that to all of the numbers here.
Second, February was more than half a degree Fahrenheit — 0.52 °F (0.29 °C) — warmer than January, which itself was “the warmest January in satellite record.”
Third, it was so hot last month that Dr. Roy Spencer of the UAH reports, “Incredibly, land areas outside the tropics in the Northern Hemisphere were a ‘whopping’ 1.46 degrees C above average, 0.5 degrees above any previous monthly anomaly.” This is a 2.6 °F warming above the 1981-2010 average — topping the previous anomaly by 0.9 °F.
Lower atmospheric warming over land outside of the tropics (vs. the 1981-2020 average) via UAH scientist Roy Spencer.
I’ve always cautioned fellow skeptics that it’s dangerous to claim no warming. There has been warming. The question is how much warming there’s been and how does that compare to what’s expected and what’s predicted.
Now we know there has been a lot of warming, it’s consistent with what scientists predicted, and, most worrisome of all, scientists now predict it will keep speeding up! Maybe we should start listening to them.
I’m sure you’ve heard from Ted Cruz and other climate science deniers that there hasn’t been any warming in the satellite record since 1998. What they really meant was there was not as much warming as expected in the lower troposphere in the (questionable) RSS data.
The UAH’s Spencer and Dr. John Christy — both leading deniers — reported just last month that the UAH data shows a “Global climate trend since Nov. 16, 1978 [of] +0.12 C [0.22 F] per decade.”
In fact out of all the temperature datasets — land, sea, weather balloons, and two from satellites (UAH and RSS) — only one dataset had shown unexpectedly slow warming in recent years, the RSS data. Unsurprisingly, that is the dataset deniers like Ted Cruz have glommed on to — despite the fact that it was widely believed the RSS data was being misanalyzed.
Indeed, back in 2011, Spencer himself explained the discrepancy between the UAH data and the RSS data on his website: “my UAH cohort and boss John Christy, who does the detailed matching between satellites, is pretty convinced that the RSS data is undergoing spurious cooling because RSS is still using the old NOAA-15 satellite which has a decaying orbit, to which they are then applying a diurnal cycle drift correction based upon a climate model, which does not quite match reality.”
The drift correction is needed because different parts of the planet are observed by satellites at different times during the day — and because satellites drift from orbit to orbit. Spencer adds that the UAH data is probably better because “We have not used NOAA-15 for trend information in years…we use the NASA Aqua AMSU [advanced microwave sounding unit], since that satellite carries extra fuel to maintain a precise orbit.”
Since Spencer is a leading climate science denier, however, he did not urge his fellow deniers to avoid using the likely flawed RSS data. Quite the reverse:
But, until the discrepancy is resolved to everyone’s satisfaction, those of you who REALLY REALLY need the global temperature record to show as little warming as possible might want to consider jumping ship, and switch from the UAH to RSS dataset.
Seriously! Spencer is such a gung-ho denier of climate science he is telling his fellow deniers who want to minimize the reality of global warming that they should not use his own data set, which he and Christy believes is superior, but instead they should use the RSS data, which they believe had a flawed diurnal cycle drift correction.
So only hard-core climate science deniers should be surprised to learn that the new study in the Journal of Climate by members of the RSS team finds that the … wait for it … the RSS data had been low-balling recent global warming because of a flawed diurnal cycle drift correction. That study, aptly titled, “Sensitivity of satellite-derived tropospheric temperature trends to the diurnal cycle adjustment,” concluded, “Previous versions of the RSS dataset have used a diurnal climatology derived from general circulation model output to remove the effects of drifting local measurement time. In this paper, we present evidence that this previous method is not sufficiently accurate, and present several alternative methods to optimize these adjustments using information from the satellite measurements themselves.”
The researchers then use an improved and optimized adjustments methodology and report:
The new dataset shows substantially increased global-scale warming relative to the previous version of the dataset, particularly after 1998. The new dataset shows more warming than most other middle tropospheric data records constructed from the same set of satellites. We also show that the new dataset is consistent with long-term changes in total column water vapor over the tropical oceans, lending support to its long-term accuracy.
In short, once a long-standing analytical error was fixed, the RSS data showed long-term global warming comparable to UAH. Here is the result:
Comparison between previous, flawed RSS global (80° S to 80° N) anomaly time series (V3.3, black line), with results using a more accurate methodology (V4.0, blue line).
The corrected dataset shows a 0.125 °C [0.225 °F] rate of warming per decade from 1979 to 2014. The corrected trend is 60% higher than the earlier, flawed rate of warming.
For those wondering why the satellite trends are slightly lower than the surface temperature trends, which exceed 0.16 °C (0.29 °F) per decade — and rising: It is always worth remembering that the surface temperature data directly measures the temperature at the surface where we live. The satellites indirectly measure the temperature of the lower atmosphere, where we don’t. Also, given that 2016 is likely to be the hottest year in the satellite record, the satellite trend — like the surface temperature trend — appears to be speeding up.
The phantom slowdown in the last of the big global temperature datasets is gone. The reality is that the globe has warmed and will continue to warm — primarily because of human-caused carbon pollution — as climate scientists have been saying for decades.
No doubt the climate science deniers will find another talking point to urge delay. But it is time for the rest of us to redouble our efforts to preserve a livable climate.
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