Nations risk baking due to the effects of climate change if they fail to take decisive and immediate action to restrain greenhouse gas emissions, an independent panel of United Nations scientists said in a report released Sunday.
Man-made emissions, the Intergovernmental Panel on Climate Change report noted, are “extremely likely to have been the dominant cause of the observed warming since the mid-20th century,” the report said, with the period ranging from 1983 through 2012 likely serving as the warmest Northern Hemisphere’s warmest 30-year period in the past 1,400 years.
The report strung together findings in four previous documents, and will give negotiators and policymakers direction as they head into U.N.-hosted climate talks next year in Paris.
Unchecked emissions would lead to a global temperature increase ranging from 3.7 to 4.8 degrees Celsius above preindustrial levels by 2100. That’s far more than the 2 degrees Celsius nations are trying to avoid through an international pact they hope to strike in Paris.
Netting an agreement is a tall task facing nations, considering a global pact has eluded the U.N. process and its nearly 200 members for 20 years. But nations have become more aware of the effects of climate change, and observers say there’s already more buy-in leading into the talks than in previous attempts to strike a deal.
The IPCC recommended some bold steps to corral climate change, as it said global emissions need to hit “near zero or below in 2100” to avoid locking in climate change.
Developing market-based policies — such as a carbon price and cap-and-trade systems — that the U.N. and other multinational organizations, such as the World Bank, have promoted received top billing in the report. Nations could also enact tax policies aimed at shifting energy use to low-carbon sources, the report said.
Phasing out fossil fuels that pump carbon dioxide and other heat-trapping gases into the atmosphere by the end of the century is likely necessary to avoid a 2-degrees-Celsius temperature increase, the report suggested. It said burning of fossil fuels and industrial activity contributed 78 percent of emissions between 1970 and 2010, and that humans accounted for more than half of the global temperature increase between 1951 and 2010.
That means renewable energy will have to provide 80 percent of the world’s power by 2050 and 90 percent by the end of the century, up from 30 percent today, the report said. Technologies such as carbon capture and storage, which trap emissions from fossil fuel-fired power plants and store them underground, will also play a role.
Countries must take such steps quickly, the report noted. That’s because taking earlier action “can substantially reduce climate change impacts in the latter decades of the 21st century and beyond,” the report said.
But nations simply aren’t doing enough to address climate change, the report said. Emissions linked to human activity have risen between 1970 and 2010, but the larger absolute increases came between 2000 and 2010 even despite countries taking more action to rein in emissions.
That’s led to Arctic ice cover receding, glaciers melting, oceans acidifying and sea levels rising, the report said. That’s altered water and precipitation systems that, in turn, affect various wildlife, marine organisms, vegetation and crops.
“Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems,” the report said.
It’s not simply enough to just prepare to withstand the effects of climate through adaptation, the report said.
The report evaluated several scenarios that based on when emissions would peak and then decline, the most aggressive — and unlikely — being in 2020. But even under the second-most ambitious option — an emissions peak in 2040 — global temperatures would like likely rise more than 1.5 degrees Celsius by 2100, with potentially irreversible effects of climate change already taking hold.
“Without additional mitigation efforts beyond those in place today, and even with adaptation, warming by the end of the 21st century will lead to high to very high risk of severe, widespread, and irreversible impacts globally,” the report noted.
Whose responsibility it is to take those steps, however, has dogged past climate negotiations.
Even the IPCC report gave a nod to that difficulty, noting that industrial powers are the ones that put most of those emissions in the air. But it’s developing nations who are less equipped to handle the effects of all that warming, and they’re also now poised to contribute a bulk of the emissions over the next century.
“Countries’ past and future contributions to the accumulation of GHGs in the atmosphere are different, and countries also face varying challenges and circumstances and have different capacities to address mitigation and adaptation,” the report said. “Mitigation and adaptation raise issues of equity, justice, and fairness. Many of those most vulnerable to climate change have contributed and contribute little to GHG emissions.”
