Blog Archive

Thursday, November 1, 2018

New study: Freak summer weather and wild jet-stream patterns are on the rise because of global warming

Simulation of jet stream pattern July 22, 2018. (
In many ways, the summer of 2018 marked a turning point, when the effects of climate change — perhaps previously on the periphery of public consciousness — suddenly took center stage. Record high temperatures spread all over the Northern HemisphereWildfires raged out of control. And devastating floods were frequent.
Michael Mann, climate scientist at Pennsylvania State University, along with colleagues, has published a new study that connects these disruptive weather extremes with a fundamental change in how the jet stream is behaving during the summer. Linked to the warming climate, the study suggests this change in the atmosphere’s steering current is making these extremes occur more frequently, with greater intensity, and for longer periods of time.
The study projects this erratic jet-stream behavior will increase in the future, leading to more severe heat waves, droughts, fires and floods.

The jet stream is changing not only because the planet is warming up but also because the Arctic is warming faster than the mid-latitudes, the study says. The jet stream is driven by temperature contrasts, and these contrasts are shrinking. The result is a slower jet stream with more wavy peaks and troughs that Mann and his study co-authors ascribe to a process known as “quasi-resonant amplification.”
The altered jet-stream behavior is important because when it takes deep excursions to the south in the summer, it sets up a collision between cool air from the north and the summer’s torrid heat, often spurring excessive rain. But when the jet stream retreats to the north, bulging heat domes form underneath it, leading to record heat and dry spells.
If the excursions in the jet stream endure long enough, it can then set the stage for floods where the jet dips, and wildfires and drought where it ascends.
“What made these events [in the summer of 2018] so devastating was not just the extreme nature of the meteorological episodes but their persistence,” Mann said in a blog post discussing the implications of the new study.
The study, published Wednesday in Science Advances, finds that these quasi-resonant amplification events — in which the jet stream exhibits this extreme behavior during the summer — are predicted to increase by 50 percent this century if emissions of carbon dioxide and other greenhouse gases continue unchecked.
Whereas previous work conducted by Mann and others had identified a signal for an increase in these events, this study for the first time examined how they may change in the future using climate model simulations.
“Looking at a large number of different computer models, we found interesting differences,” said Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research and a co-author of the study, in a news release. “Distinct climate models provide quite diverging forecasts for future climate resonance events. However, on average they show a clear increase in such events.”
In an email, Mann said climate models aren’t fully capturing the phenomenon, and, for this reason, we should expect weather extremes “beyond what is typically projected” into the future.
Mann added the existing analyses that attempt to uncover the role of climate change in recent extreme events “are under-attributing the role that climate change is having … because they are not capturing the key mechanism responsible.”
Mann said in his blog commentary that he was particularly struck by the jet-stream behavior in the summer. “In summer 2018, I would argue, that signal was no longer subtle,” he said. “It played out in real time on our television screens and newspaper headlines in the form of an unprecedented hemisphere-wide pattern of extreme floods, droughts, heat waves and wildfires.”
Although model projections suggest these extreme jet-stream patterns will increase as the climate warms, the study concluded that their increase can be slowed if greenhouse gas emissions are reduced along with particulate pollution in developing countries. “[T]he future is still very much in our hands when it comes to dangerous and damaging summer weather extremes,” Mann said. “It’s simply a matter of our willpower to transition quickly from fossil fuels to renewable energy.”

Dr. Jennifer Francis, a climate researcher at Rutgers University who has published work exhibiting changing jet-stream behavior because of climate change, found the results of this new study compelling. “This work takes a big step toward understanding the spate of deadly extreme weather events during recent summers — heat waves, floods and droughts,” she said in an email.

Posts in October 2018

2018 (32)

Wednesday, October 31, 2018

UK scientists willing to risk going to prison to fight for climate action - say there's nothing left to lose

A group of British scientists and their supporters is willing to risk a prison term to press governments to tackle climate change and environmental crisis.
by Alex Kirby, Climate News Network, October 31, 2018
LONDON − A growing number of British academics, writers and activists say they are ready to go to prison in support of their demands for action on the environment.
Scientists are not normally renowned for their political activism, and the UK is hardly a hotbed of determined and risky protest against its rulers. But, if this group of nearly 100 British scientists and their backers is right, all that may be on the brink of changing.
Today sees the launch of ExtinctionRebellion, which describes itself as an international movement using mass civil disobedience to force governments to enter World War Twolevel mobilization mode, in response to climate breakdown and ecological crisis.
The group is launching a Declaration of Rebellion against the UK government “for criminal inaction in the face of climate change catastrophe and ecological collapse” at the Houses of Parliament in central London.
“We need ExtinctionRebellion as part of the mosaic of responses to the extremely precarious situation we now find ourselves in”
From today it promises “repeated acts of disruptive, non-violent civil disobedience” if the government does not respond seriously to its demands, and says “there will be mass arrests.”
“Now is the time because we are out of time. There is nothing left to lose.”
The group’s demands include the declaration by the UK government of a state of emergency, action to create a zero carbon economy by 2025, and the establishment of a national assembly of “ordinary people” to decide what the zero carbon future will look like.
Based on the science, it says, humans have ten years at the most to reduce carbon dioxide emissions to zero, or the human race and most other species will be at high risk of extinction within decades.
“Children alive today in the UK will face unimaginable horrors as a result of floods, wildfires, extreme weather, crop failures and the inevitable breakdown of society when the pressures are so great. We are unprepared for the danger our future holds.”
Ecological crisis
On 30 October 2018, the Worldwide Fund for Nature reported that humanity has wiped out 60% of animal populations since 1970, something it says threatens the survival of civilization. 
ExtinctionRebellion says the loss of species shows that “the planet is in ecological crisis, and we are in the midst of the sixth mass extinction event this planet has experienced.”
Its members say they are willing to make personal sacrifices, to be arrested and to go to prison. They hope to inspire similar actions around the world and believe this global effort must begin in the UK, today, where the industrial revolution began.
Many of the Declaration’s signatories are well-known in the academic world. They include Danny Dorling, professor of geography at the University of Oxford, and Dr Ian Gibson, who formerly chaired the Parliamentary science and technology select committee. Serving Members of Parliament who support ExtinctionRebellion include the Green Party’s Caroline Lucas.
Other backers are probably better-known for their achievements beyond science, including the former Archbishop of Canterbury, Rowan Williams, now the Master of Magdalene College at the University of Cambridge, and the journalist George Monbiot.
Cry of desperation
Another supporter is Andrew Simms of the New Weather Institute. He told the Climate News Network: “This is almost a cry of desperation. People are bewildered. But almost every profound change in British society, from the abolition of slavery to the improvement of shipping safety, has involved people risking arrest.
“The signs I am getting from the UK government now are that it is a reckless administration putting its own people and others at risk by putting climate change virtually nowhere.
“The Declaration alone won’t bring about change: we’ll need people working practically to make change happen on the ground. But we need ExtinctionRebellion as part of the mosaic of responses to the extremely precarious situation we now find ourselves in.”
Simms, convinced that an entirely new potential for rapid societal change now exists, says: “We know what’s needed, and the resources to do it are there. ExtinctionRebellion is one example of how new ideas can spread quickly and rapid shift − and radical action − can come closer.”

Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composit

Nature, 563 (31 October 2018) 105-108

Quantification of ocean heat uptake from changes in atmospheric O2 and COcomposit


The ocean is the main source of thermal inertia in the climate system1. During recent decades, ocean heat uptake has been quantified by using hydrographic temperature measurements and data from the Argo float program, which expanded its coverage after 20072,3. However, these estimates all use the same imperfect ocean dataset and share additional uncertainties resulting from sparse coverage, especially before 20074,5. Here we provide an independent estimate by using measurements of atmospheric oxygen (O2) and carbon dioxide (CO2)—levels of which increase as the ocean warms and releases gases—as a whole-ocean thermometer. We show that the ocean gained 1.33 ± 0.20  × 1022 joules of heat per year between 1991 and 2016, equivalent to a planetary energy imbalance of 0.83 ± 0.11 watts per square metre of Earth’s surface. We also find that the ocean-warming effect that led to the outgassing of O2 and CO2 can be isolated from the direct effects of anthropogenic emissions and CO2 sinks. Our result—which relies on high-precision O2 measurements dating back to 19916—suggests that ocean warming is at the high end of previous estimates, with implications for policy-relevant measurements of the Earth response to climate change, such as climate sensitivity to greenhouse gases7 and the thermal component of sea-level rise8.


  1. 1.
    IPCC. Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) (Cambridge Univ. Press, Cambridge, 2013).
  2. 2.
    Abraham, J. P. et al. A review of global ocean temperature observations: implications for ocean heat content estimates and climate change. Rev. Geophys51, 450–483 (2013).
  3. 3.
    Riser, S. C. et al. Fifteen years of ocean observations with the global Argo array. Nat. Clim. Chang e 6, 145–153 (2016).
  4. 4.
    Boyer, T. et al. Sensitivity of global upper-ocean heat content estimates to mapping methods, XBT bias corrections, and baseline climatologies. J. Clim29, 4817–4842 (2016).
  5. 5.
    Cheng, L. et al. XBT science: assessment of instrumental biases and errors. Bull. Am. Meteorol. Soc97, 924–933 (2016).
  6. 6.
    Keeling, R. F. & Manning, A. C. in Treatise on Geochemistry 385–404 (Elsevier, Oxford, 2014).
  7. 7.
    Forster, P. M. Inference of climate sensitivity from analysis of Earth’s energy budget. Annu. Rev. Earth Planet. Sci44, 85–106 (2016).
  8. 8.
    Church, J. A. et al. in Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) 1137–1216 (IPCC, Cambridge Univ. Press, Cambridge, 2013).
  9. 9.
    Ishii, M. et al. Accuracy of global upper ocean heat content estimation expected from present observational data sets. Sci. Online Lett. Atmos13, 163–167 (2017).
  10. 10.
    Johnson, G. C. et al. Ocean heat content. Am. Meteorol. Soc. Bull98, S66–S68 (2017).
  11. 11.
    Desbruyères, D. G., Purkey, S. G., McDonagh, E. L., Johnson, G. C. & King, B. A. Deep and abyssal ocean warming from 35 years of repeat hydrography. Geophys. Res. Lett43, 10356–10365 (2016).
  12. 12.
    Cheng, L. et al. Improved estimates of ocean heat content from 1960 to 2015. Sci. Adv3, e1601545 (2017).
  13. 13.
    Allan, R. P. et al. Changes in global net radiative imbalance 1985–2012. Geophys. Res. Lett41, 5588–5597 (2014).
  14. 14.
    Palmer, M. D. Reconciling estimates of ocean heating and Earth’s radiation budget. Curr. Clim. Change Rep3, 78–86 (2017).
  15. 15.
    Loeb, N. G. et al. Observed changes in top-of-the-atmosphere radiation and upper-ocean heating consistent within uncertainty. Nat. Geosci5, 110–113 (2012).
  16. 16.
    Battle, M. et al. Measurements and models of the atmospheric Ar/N2 ratio. Geophys. Res. Lett30, 1786 (2003).
  17. 17.
    Ritz, S. P., Stocker, T. F. & Severinghaus, J. P. Noble gases as proxies of mean ocean temperature: sensitivity studies using a climate model of reduced complexity. Quat. Sci. Rev30, 3728–3741 (2011).
  18. 18.
    Resplandy, L. et al. Constraints on oceanic meridional heat transport from combined measurements of oxygen and carbon. Clim. Dyn47, 3335–3357 (2016); erratum 49, 4317 (2017).
  19. 19.
    Stephens, B. B. et al. Testing global ocean carbon cycle models using measurements of atmospheric O2 and CO2 concentration. Glob. Biogeochem. Cycles12, 213–230 (1998).
  20. 20.
    Le Quéré, C. et al. Global carbon budget 2016. Earth Syst. Sci. Data 8, 605–649 (2016).
  21. 21.
    DeVries, T. The oceanic anthropogenic CO2 sink: storage, air-sea fluxes, and transports over the industrial era. Glob. Biogeochem. Cycles 28, 631–647 (2014).
  22. 22.
    Wang, R. et al. Influence of anthropogenic aerosol deposition on the relationship between oceanic productivity and warming. Geophys. Res. Lett42, 10745–10754 (2015).
  23. 23.
    Rietbroek, R., Brunnabend, S.-E., Kusche, J., Schröter, J. & Dahle, C. Revisiting the contemporary sea-level budget on global and regional scales. Proc. Natl Acad. Sci. USA 113, 1504–1509 (2016).
  24. 24.
    IPCC. Climate Change 2007: Synthesis Report (eds Core Writing Team, Pachauri, R. K. & Reisinger, A.) (IPCC, Geneva, 2008).
  25. 25.
    Keeling, R. F. & Severinghaus, J. P. in The Carbon Cycle (eds Wigley, T. M. L. & Schimel, D.) 134–140 (Cambridge Univ. Press, New York, 2000).
  26. 26.
    Resplandy, L., Séférian, R. & Bopp, L. Natural variability of CO2 and O2 fluxes: what can we learn from centuries-long climate models simulations? J. Geophys. Res. Oceans 120, 384–404 (2015).
  27. 27.
    Eddebbar, Y. A. et al. Impacts of ENSO on air-sea oxygen exchange: observations and mechanisms. Glob. Biogeochem. Cycles 31, 2017GB005630 (2017).
  28. 28.
    Keeling, R. F. & Garcia, H. E. The change in oceanic O2 inventory associated with recent global warming. Proc. Natl Acad. Sci. USA 99, 7848–7853 (2002).
  29. 29.
    Bopp, L., Le Quéré, C., Heimann, M., Manning, A. C. & Monfray, P. Climate-induced oceanic oxygen fluxes: implications for the contemporary carbon budget. Glob. Biogeochem. Cycles 16, 1022 (2002).
  30. 30.
    Keeling, C. D., Piper, S. C., Whorf, T. P. & Keeling, R. F. Evolution of natural and anthropogenic fluxes of atmospheric CO2 from 1957 to 2003. Tellus B Chem. Phys. Meterol63, 1–22 (2011).
  31. 31.
    Levitus, S. et al. World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010. Geophys. Res. Lett39, L10603 (2012).
  32. 32.
    Olsen, A. et al. The Global Ocean Data Analysis Project version 2 (GLODAPv2)—an internally consistent data product for the world ocean. Earth Syst. Sci. Data 8, 297–323 (2016).
  33. 33.
    Severinghaus, J. P. Studies of the Terrestrial O 2 and Carbon Cycles in Sand Dune Gases and in Biosphere. PhD Thesis, Columbia Univ. (1995).
  34. 34.
    Hamme, R. C. & Keeling, R. F. Ocean ventilation as a driver of interannual variability in atmospheric potential oxygen. Tellus B Chem. Phys. Meterol60, 706–717 (2008).
  35. 35.
    Andres, R. J., Boden, T. A. & Higdon, D. A new evaluation of the uncertainty associated with CDIAC estimates of fossil fuel carbon dioxide emission. Tellus B Chem. Phys. Meterol66, 23616 (2014).
  36. 36.
    Keeling, R. F., Manning, A. C., Paplawsky, W. J. & Cox, A. C. On the long-term stability of reference gases for atmospheric O2/N2 and CO2 measurements. Tellus B Chem. Phys. Meterol59, 3–14 (2007).
  37. 37.
    Ballantyne, A. P. et al. Audit of the global carbon budget: estimate errors and their impact on uptake uncertainty. Biogeosciences 12, 2565–2584 (2015).
  38. 38.
    Bronselaer, B., Winton, M., Russell, J., Sabine, C. L. & Khatiwala, S. Agreement of CMIP5 simulated and observed ocean anthropogenic CO2 uptake. Geophys. Res. Lett44, 12298–12305 (2017).
  39. 39.
    Oeschger, H., Siegenthaler, U., Schotterer, U. & Gugelmann, A. A box diffusion model to study the carbon dioxide exchange in nature. Tellus 27, 168–192 (1975).
  40. 40.
    MacFarling Meure, C. et al. Law Dome CO2, CH4 and N2O ice core records extended to 2000 years BP. Geophys. Res. Lett33, L14810 (2006).
  41. 41.
    Wang, D., Gouhier, T. C., Menge, B. A. & Ganguly, A. R. Intensification and spatial homogenization of coastal upwelling under climate change. Nature 518, 390–394 (2015).
  42. 42.
    Ito, T., Nenes, A., Johnson, M. S., Meskhidze, N. & Deutsch, C. Acceleration of oxygen decline in the tropical Pacific over the past decades by aerosol pollutants. Nat. Geosci9, 443–447 (2016).
  43. 43.
    Jickells, T. D. et al. A reevaluation of the magnitude and impacts of anthropogenic atmospheric nitrogen inputs on the ocean. Glob. Biogeochem. Cycles 31, 289–305 (2017).
  44. 44.
    Somes, C. J., Landolfi, A., Koeve, W. & Oschlies, A. Limited impact of atmospheric nitrogen deposition on marine productivity due to biogeochemical feedbacks in a global ocean model. Geophys. Res. Lett43, 4500–4509 (2016).
  45. 45.
    Aumont, O., Ethé, C., Tagliabue, A., Bopp, L. & Gehlen, M. PISCES-v2: an ocean biogeochemical model for carbon and ecosystem studies. Geosci. Model Dev8, 2465–2513 (2015).
  46. 46.
    Talley, L. D. et al. Changes in ocean heat, carbon content, and ventilation: a review of the first decade of GO-SHIP global repeat hydrography. Annu. Rev. Marine Sci8, 185–215 (2016).
  47. 47.
    Sarmiento, J. L. & Gruber, N. Sinks for anthropogenic carbon. Phys. Today 55, 30–36 (2002).
  48. 48.
    Garcia, H. E. & Gordon, L. I. Oxygen solubility in seawater: better fitting equations. Limnol. Oceanogr37, 1307–1312 (1992).
  49. 49.
    Gruber, N., Sarmiento, J. L. & Stocker, T. F. An improved method for detecting anthropogenic CO2in the oceans. Glob. Biogeochem. Cycles 10, 809–837 (1996).
  50. 50.
    Dunne, J. P. et al. GFDL’s ESM2 global coupled climate–carbon Earth system models. Part I: physical formulation and baseline simulation characteristics. J. Clim25, 6646–6665 (2012).
  51. 51.
    Dunne, J. P. et al. GFDL’s ESM2 global coupled climate–carbon Earth system models. Part II: carbon system formulation and baseline simulation characteristics. J. Clim26, 2247–2267 (2013).
  52. 52.
    Séférian, R., Iudicone, D., Bopp, L., Roy, T. & Madec, G. Water mass analysis of effect of climate change on air–sea CO2 fluxes: the Southern Ocean. J. Clim25, 3894–3908 (2012).
  53. 53.
    Kay, J. E. et al. The Community Earth System Model (CESM) large ensemble project: a community resource for studying climate change in the presence of internal climate variability. Bull. Am. Meteorol. Soc96, 1333–1349 (2015).
  54. 54.
    Keller, D. P., Oschlies, A. & Eby, M. A new marine ecosystem model for the University of Victoria Earth System Climate Model. Geosci. Model Dev5, 1195–1220 (2012).
  55. 55.
    Bopp, L. et al. Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models. Biogeosciences 10, 6225–6245 (2013).
  56. 56.
    Keller, D. P., Kriest, I., Koeve, W. & Oschlies, A. Southern Ocean biological impacts on global ocean oxygen. Geophys. Res. Lett43, 6469–6477 (2016).
  57. 57.
    Long, M. C., Deutsch, C. & Ito, T. Finding forced trends in oceanic oxygen. Glob. Biogeochem. Cycles30, 381–397 (2016).
  58. 58.
    Taylor, K. E., Stouffer, R. J. & Meehl, G. A. An overview of CMIP5 and the experiment design. Bull. Am. Meteorol. Soc93, 485–498 (2012).
  59. 59.
    Moore, J. K., Lindsay, K., Doney, S. C., Long, M. C. & Misumi, K. Marine ecosystem dynamics and biogeochemical cycling in the Community Earth System Model [CESM1(BGC)]: comparison of the 1990s with the 2090s under the RCP4.5 and RCP8.5 scenarios. J. Clim26, 9291–9312 (2013).
  60. 60.
    Rödenbeck, C., Le Quéré, C., Heimann, M. & Keeling, R. F. Interannual variability in oceanic biogeochemical processes inferred by inversion of atmospheric O2/N2 and CO2 data. Tellus B Chem. Phys. Meterol60, 685–705 (2008).
  61. 61.
    Hamme, R. C. Mechanisms controlling the global oceanic distribution of the inert gases argon, nitrogen and neon. Geophys. Res. Lett29, 35-1–35-4 (2002).
  62. 62.
    Trenberth, K. E., Fasullo, J. T., von Schuckmann, K. & Cheng, L. Insights into Earth’s energy imbalance from multiple sources. J. Clim29, 7495–7505 (2016).
  63. 63.
    WCRP Global Sea Level Budget Group. Global sea level budget 1993–present. Earth Syst. Sci. Data 10, 1551–1590 (2018).
  64. 64.
    Morice, C. P., Kennedy, J. J., Rayner, N. A. & Jones, P. D. Quantifying uncertainties in global and regional temperature change using an ensemble of observational estimates: the HadCRUT4 data set. J. Geophys. Res. Atmos117, D08101 (2012).
  65. 65.
    Hansen, J., Ruedy, R., Sato, M. & Lo, K. Global surface temperature change. Rev. Geophys48, RG4004 (2010).
  66. 66.
    Vose, R. S. et al. NOAA’s merged land–ocean surface temperature analysis. Bull. Am. Meteorol. Soc93, 1677–1685 (2012).
  67. 67.
    Keeling, R. F., Körtzinger, A. & Gruber, N. Ocean deoxygenation in a warming world. Annu. Rev. Mar. Sci2, 199–229 (2010).
  68. 70.
    Schmidtko, S., Stramma, L. & Visbeck, M. Decline in global oceanic oxygen content during the past five decades. Nature 542, 335–339 (2017).
  69. 68.
    Helm, K. P., Bindoff, N. L. & Church, J. A. Observed decreases in oxygen content of the global ocean. Geophys. Res. Lett38, L23602 (2011).
  70. 69.
    Ito, T., Minobe, S., Long, M. C. & Deutsch, C. Upper ocean O2 trends: 1958–2015. Geophys. Res. Lett44, 4214–4223 (2017).