Dr. IPCC provides diagnosis, prognosis, and remedy

The 2013 Intergovernmental Panel on Climate Change report released last week is clear: climate change is happening, now, and it is not pretty. “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased…. Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850.”

This distressing trend was already obvious 25 years ago, when Toronto hosted one of the first international climate change gatherings. The event sparked the formation of Toronto Atmospheric Fund with a mandate and endowment to advance local solutions to climate change. While the City of Toronto’s emissions are down by an impressive 15%, the global trend is not as healthy.

The report — actually various volumes of reports, plus the traditional Summary for Policy-Makers  — is the compilation of thousands of studies and models and, with the exception of a few skeptics/deniers, presents a scientific consensus on climate change. The report says that “The atmospheric concentrations of carbon dioxide (CO2), methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. CO2 concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions.”

Just reading the highlights of the summary is sobering, so here they are, quoted:

  • In the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the last 1400 years (medium confidence).
  • Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010 (high confidence). It is virtually certain that the upper ocean (0−700 m) warmed from 1971 to 2010, and it likely warmed between the 1870s and 1971. The global ocean will continue to warm during the 21st century. The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification. Heat will penetrate from the surface to the deep ocean and affect ocean circulation.
  • Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent (high confidence). It is very likely that the Arctic sea ice cover will continue to shrink and thin and that Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises. Global glacier volume will further decrease.
  • The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence). Over the period 1901–2010, global mean sea level rose by 0.19 [0.17 to 0.21] meters. Global mean sea level will continue to rise during the 21st century. Under all RCP scenarios the rate of sea level rise will very likely exceed that observed during 1971–2010 due to increased ocean warming and increased loss of mass from glaciers and ice sheets.
  •  Climate change will affect carbon cycle processes in a way that will exacerbate the increase of CO2 in the atmosphere (high confidence). Further uptake of carbon by the ocean will increase ocean acidification.
  • Changes in the global water cycle in response to the warming over the 21st century will not be uniform. The contrast in precipitation between wet and dry regions and between wet and dry seasons will increase, although there may be regional exceptions
  • Total radiative forcing is positive, and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO2 since 1750.

The IPCC is also unequivocal about the cause of climate change. We have seen the enemy, and it is us. “Human influence on the climate system is clear. This is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding of the climate system. Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes. This evidence for human influence has grown since AR4 (the last report). It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.”

We know the symptoms: hotter, wetter, stormier, more acidic, increasingly uncomfortable and unlivable weather conditions, whatever species you are, wherever you live. And we know the cause: “Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system.”

Dr. IPCC is also pretty clear about the medicine: “Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.”

The good news is that taking the medicine has beneficial side-effects: more efficient buildings and less money wasted on heating the great outdoors; cleaner air and fewer deaths from asthma caused by coal-fired smog; better transit and less stress and wasted time on congested roads. It’s time to listen to the planet, the scientists, and what we actually can see happening around us and find the silver lining.


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