Joe Romm: Stunning NASA chart shows how fast the ground beneath our feet is heating up

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 this 2009 study, “Understanding Land–Sea Warming Contrast in Response to Increasing Greenhouse Gases.” Then try this 2013 study.

https://thinkprogress.org/global-warming-now-twice-as-fast-over-land-than-the-ocean-nasa-chart-shows-52b4afe01345/