Saturday’s snow in South Carolina and other states not accustomed to seeing the white stuff in early November probably resulted in climate-change deniers making silly comments about the unusual weather being proof that there is no such thing as global warming.
But Sunday’s AR5 report (Synthesis Report of the Intergovernmental Panel on Climate Change) released by the United Nations should wipe the smirk from the deniers’ faces.
“The globe is heading toward ‘severe, pervasive, and irreversible’ climate change impacts if left ‘unchecked,’ according to a new United Nations report,” read the first sentence in The Hill’s coverage of the report.
Here are some of the findings of this comprehensive report written by over 800 scientists from around the world.
On climate change
The 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, and sea level has risen.
Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. The period from 1983 to 2012 was very likely the warmest 30-year period of the last 800 years in the Northern Hemisphere, where such assessment is possible and likely the warmest 30-year period of the last 1400 years.
Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass. Glaciers have continued to shrink almost worldwide. Northern Hemisphere spring snow cover has continued to decrease in extent.
On the cause
Anthropogenic greenhouse gas emissions have increased since the pre-industrial era driven largely by economic, and population growth. From 2000 to 2010 emissions were the highest in history. Historical emissions have driven atmospheric concentrations of carbon dioxide, methane and nitrous oxide, to levels that are unprecedented in at least the last 800,000 years, leading to an uptake of energy by the climate system.
The evidence for human influence on the climate system has grown since AR4 (released in 2007). 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, and in global mean sea-level rise; and it is extremely likely to have been the dominant cause of the observed warming since the mid-20th century.
On the impact
In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Impacts are due to observed climate change, irrespective of its cause, indicating the sensitivity of natural and human systems to changing climate.
Climate change will amplify existing risks and create new risks for natural and human systems. Risks are unevenly distributed and are generally greater for disadvantaged people and communities in countries at all levels of development. Increasing magnitudes of warming increase the likelihood of severe, pervasive, and irreversible impacts for people, species and ecosystems. Continued high emissions would lead to mostly negative impacts for biodiversity, ecosystems services, and economic development and amplify risks for livelihoods and for food and human security.
This report is a clarion call for the world to quickly start reducing carbon pollution, for communities to begin serious resiliency planning and, in the style of New Jersey Governor Chris Christie, for all of us to tell deniers to sit down and shut up.