The UN Climate Report: What You Need to Know

What's This?

Giant machines dig for brown coal at the open-cast mining Garzweiler in front of a smoking power plant near the city of Grevenbroich in western Germany on April 3, 2014.

Image: Martin Meissner/Associated Press

By Andrew Freedman2014-04-14 20:29:40 UTC

On Sunday, the U.N. Intergovernmental Panel on Climate Change (IPCC) released the final installment of a massive report laying out just how feasible it is for the global community to limit manmade global warming to below dangerous levels.

Like the previous two installments, published in September of last year and March, this report contains extremely dense, technical material.

See also: We're Running Out of Time to Stop Global Warming, UN Says

Yet its contents are hugely important for the public and policymakers. It lays out the case for why drastic emissions cuts are needed, starting within the next decade, in order to have a decent chance of limiting the amount — and the pace — of global warming.

First, here's the good news from the report. Meeting the target of keeping global warming to less than 3.6 degrees Fahrenheit above preindustrial levels can be done — if we take action now.

Here's a breakdown of some of the latest report's most important findings.

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  The window of opportunity to avert a "dangerous" amount of global warming is rapidly closing: We have just about a decade left to bend the upward curve of greenhouse gas emissions. Attempts to reduce emissions significantly so far have not succeeded.

  
  


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  Pathways of global GHG emissions (GtCO2eq/yr) in baseline and mitigation scenarios for different long-term concentration levels.

  
  


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  The longer we wait, the fewer options we will have: After 2030, for example, many of the more than 1,000 policy scenarios the scientists examined would not succeed in limiting manmade global warming to 3.6 degrees Fahrenheit or less, which is the goal that world leaders agreed to during the Copenhagen climate summit in 2009. In other words, the world will have fewer options available the longer we wait to cut emissions.

  
  


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  We're definitely on the wrong track: The world is on course to see an increase in global average surface temperatures of up to 9 degrees Fahrenheit by the end of this century. This could have disastrous consequences by dramatically raising global sea levels, melting land-based ice sheets, and leading to more heat waves and extreme precipitation events, among other impacts.

  
  


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  We are already seeing climate change impacts worldwide, including the increased likelihood and severity of some extreme weather events like heat waves and heavy precipitation events, and the global average surface temperature has increased by just 1.6 degrees Fahrenheit since 1901.

  
  


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  We already have most of the technologies we need: We don't need to — in fact we shouldn't — wait for some miracle technological solution to climate change, since tools to burn energy more cleanly and use energy more efficiently already exist. However, in most climate scenarios, carbon capture and storage technology needs to be employed to bring emissions to lower levels. Such technology, which would capture carbon dioxide emissions before it escapes a power plant and bury it deep underground, is not yet proven on a commercial scale.

  
  


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  Emisions cuts may not break the bank: Although economic studies of how much it will cost to minimize global warming vary, but the study says that aggressive emissions cuts would only shave off between 0.04% and 0.14% from consumption growth during the century.

  
  


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  Emissions need to trend in the opposite direction, ASAP: Total manmade greenhouse-gas emissions were the highest in human history from 2000 to 2010, and reached 49 gigatonnes of carbon dioxide equivalent per year in 2010. The vast majority of that, or about 78%, has come from burning fossil fuels for energy, with smaller amounts coming from deforestation, agriculture and other sources.

  
  

  To have a good chance of limiting warming to less than 3.6 degrees Fahrenheit compared to pre-industrial levels, carbon-dioxide levels would have to be kept below 450 parts per million (ppm) by 2100. (They are currently just above 400 ppm.)

  
  

  This would require emissions cuts of 40% to 70% by 2050, and near zero emissions by 2100. Accomplishing this without paying an exorbitant cost would require that actions begin within the next decade.

  
  


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  Coal is reversing energy sector gains: While coal use is plummeting in the U.S., the increased use of coal in developing countries (much of it shipped from the U.S.) as a cheap source of electricity has reversed trends toward a progressively less carbon intensive energy sector.

  
  


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  Business as usual is not climate as usual: Atmospheric carbon-dioxide levels are currently just above 400 parts per million (ppm), and are already the highest in at least the past 800,000 years. Under a business as usual scenario, the report says carbon can be expected to soar to higher than 1,300 ppm by 2100. This could lead to global warming ranging from 4.5 degrees Fahrenheit to 14 degrees Fahrenheit above pre-industrial levels by the end of this century, when the full range of scientific uncertainty is taken into account.

  
  


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  Total manmade greenhouse gas emissions (GtCO2eq/yr) by economic sectors. The emissions data from Agriculture, Forestry and Other Land Use (AFOLU) includes land-based CO2 emissions from forest fires, peat fires and peat decay.

  
  


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  We're on a CO2 binge: About half of all cumulative manmade carbon-dioxide emissions between 1750 and 2010 happened during the past 40 years. Since carbon dioxide remains in the atmosphere for as many as 1,000 years, the cumulative emissions are what determines how much warming we’re ultimately in store for — and we’ve already burned about half of the carbon budget that would keep warming to less than 3.6 degrees Fahrenheit.

  
  


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  If those in favor of acting to limit climate change feel vindicated by the report, that's not the same as feeling optimistic. Saving the world from climate change may be technically feasible, but the political will to take the hard and necessary decisions — by the time we have to take them — still seems to be lacking.

  
  

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  Topics: Climate, climate science, climate study, greenhouse gases, IPCC, United Nations, U.S., US & World, World