Window to Cut Global Warming Is Narrowing, UN Report Finds

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In this picture taken Thursday, April 3, 2014, giant machines dig for brown coal at the open-cast mining Garzweiler near the city of Grevenbroich, western Germany. Coal is a major contributor of greenhouse gases.

Image: Martin Meissner/Associated Press

By Andrew Freedman2014-04-13 20:45:25 UTC

The window of opportunity to avoid an amount of global warming that global leaders have agreed would be “dangerous” is rapidly closing, with just a decade left for the world to begin undertaking sweeping technological and governmental actions to rein in emissions of global-warming gases such as carbon dioxide, according to a new United Nations report released Sunday in Berlin. After that, it becomes far more difficult and expensive to cut emissions sufficiently to avoid dangerous amounts of warming.

Given recent emissions and temperature trends, the world is on track to see an increase in global average surface temperatures of up to 9 degrees Fahrenheit by the end of this century, the report says. 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.

The report, the third and final installment of the latest comprehensive review of climate science from the Nobel Prize-winning UN Intergovernmental Panel on Climate Change’s (IPCC), analyzes more than 1,000 scenarios of potential economic growth and environmental changes to determine how to minimize global warming.

The report is simultaneously optimistic and grim in tone, since it concludes there is time and pre-existing technological knowledge available to meet the goals that leaders set out in a non-binding agreement in 2009, yet lays bare the sheer scope of the challenges that lie ahead.

IPCC Panel

Ottmar Edenhofer, co-chairman of the IPCC Working Group III, Jochen Flasbarth, State Secretary of the German Environment Ministry, Rejendra K. Pachauri, chairman of the IPCC and Jochen Schuette, State Secretary of the German Science Ministry, from left, pose for the media prior to a meeting of the UN IPCC in Berlin, Germany on April 7, 2014.

Image: Michael Sohn/Associated Press

The central task for scientists, engineers and policymakers is to figure out how to facilitate continued economic and population growth, without also causing emissions to skyrocket at the same time, the report says.

Figuring out how to do that gets at the core of global-development issues and the sharp climate-policy divide between industrialized and developing nations. Government representatives meeting in Berlin last week to approve the report, objected to language in the widely read summary for policymakers that suggested developing countries have to do more to reduce their greenhouse gas emissions, according to the New York Times. However, such language remained in the lengthy technical report. Text discussing transfers of funding to developing countries to assist them in growing their economies without boosting emissions was also removed from the summary,

The IPCC’s fifth assessment provides the foundation for upcoming rounds of negotiations to craft a new global climate treaty, starting with a high-level climate summit in New York this September, and culminating in another summit in Paris next year. The next treaty is supposed to be enforced by 2020.

U.S. Secretary of State John Kerry said the report underscores the need for action by 2015.

“So many of the technologies that will help us fight climate change are far cheaper, more readily available and better performing than they were when the last IPCC assessment was released less than a decade ago,” Kerry said in a statement. “This report makes very clear we face an issue of global willpower, not capacity.”

Here are some of the report’s key findings:

We’re not headed in the right direction, if we want to limit global warming: 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.

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.

Total annual manmade greenhouse gas emissions (GtCO2eq/yr) by groups of gases, 1970 to 2010. At the right side of the figure, greenhouse-gas emissions in 2010 are shown again broken down into these components with the associated uncertainties (90% confidence interval) indicated by the error bars.

The last 40 years have brought a carbon boom the likes of which we’ve never experienced before: About half of all cumulative manmade carbon-dioxide emissions between 1750 and 2010 occurred during the past 40 years. Since carbon dioxide remains in the atmosphere for hundreds to more than 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. That was the target world leaders agreed to in 2009 during a contentious round of UN climate talks.

Don’t place all the blame on population growth: The biggest factors contributing to the recent spike in greenhouse-gas emissions are economic and population growth, with economic growth playing the largest role in the last decade. The report singles out the increased use of coal for electricity as the reason why the decarbonization of energy production has essentially halted.

Emissions would have to be slashed ASAP to meet the 3.6 degree Fahrenheit target: 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 ppm by 2100. This would require emissions cuts of 40% to 70% by 2050, and near or below zero emissions by 2100. Accomplishing this without paying an exorbitant cost would require that actions begin within the next decade.

Yes, that does say “near or below zero by 2100”: To keep emissions low enough to avert the worst potential consequences of manmade global warming, emissions don’t just have to come down, they have to hit the floor and keep on going, the IPCC says.

The longer we wait to enact emissions cuts, the worse climate change will be, and the more expensive it will be: Waiting until 2030 to start reducing emissions would eliminate many of the more than 1,000 policy scenarios examined in this report, and increase the costs of cutting emissions, as well as the costs of climate impacts. Part of the reason for this is that investments made today in power plants and buildings will lock in place particular levels of carbon emissions for up to a half-century, since such structures last a long time.

“A decision to put up a building is a multidecadal decision,” Chris Pyke, one of the report's authors, told Mashable. “We’re locking in choices, and we’re locking out the ability to do something else.”

Renewable energy sources need to grow — and fast: Most of the scenarios that involve relatively modest amounts of global warming include a rapid ramp-up of renewable-energy sources, to where they contribute about 80% of the global electricity supply by 2050. Renewable-energy technologies accounted for just over half of the new electricity-generating capacity added worldwide in 2012.

Natural gas can be part of the solution: Replacing coal-fired power plants with natural-gas plants can reduce greenhouse-gas emissions, as long as high amounts of emissions do not occur when drilling for and transporting gas supplies.

Efficiency is also key: Huge reductions in greenhouse gas emissions can be made in the buildings sector, since we already have the technology to make buildings more efficient. For example, 70% of New York City’s emissions come from the buildings sector, according to Pyke.