Temperatures could rise by 1.5 degrees Celsius as early as 2030 if global warming continues at its current pace and the world fails to take rapid and unprecedented measures to stem the increase, experts warned in a landmark UN report on Monday.
The report is seen as the main scientific guide for government policymakers on how to implement the 2015 Paris Agreement, which aims to limit the rise in global average temperatures to “well below” 2C above pre-industrial levels, while seeking to tighten the goal to 1.5C. The report was finalised at a special meeting in South Korea last week.
Meeting the 1.5C limit would demand “rapid, far-reaching and unprecedented change in all aspects of society”, the panel said. Temperatures would be 1.5C higher between 2030 and 2052 if the world continues at its current pace, it warned.
The report triggered calls for policymakers to immediately end all fossil fuel subsidies, set a price on carbon, and adopt renewable energy and green technologies.
“This report is not a wake-up call, it is a ticking timebomb,” said Gro Harlem Brundtland, Acting Chair of The Elders in a statement. “Climate activists have been calling for decades for leaders to show responsibility and take urgent action, but we have barely scratched the surface of what needs to be done. Further failure would be an unconscionable betrayal of the planet and future generations.”
Temperatures have already risen an average 1C since the mid-1800s as industrialisation fuels the growth of carbon dioxide emissions (CO2), the main greenhouse gas blamed for climate change.
An increase of 1.5C will still carry climate-related risks for nature and humanity, but at a lower level than a rise of 2C, the report summary said. Experts say meeting that target is critical not only for the environment, but also to safeguard poor and vulnerable communities on the front line of the climate threat.
“Scientists are increasingly aware that every half degree of warming matters,” Chris Weber, WWF’s global climate and energy lead scientist, said in a statement.
“We must have laser focus on delivering on 1.5 degrees and this report provides a pathway to get there. We need to halve greenhouse gas emissions globally by 2030 and cut coal use by two-thirds by the same date.”
The report was prepared at the request of governments when the global pact to tackle climate change was agreed upon in Paris nearly three years ago. It is based on more than 6,000 scientific references and contributions from thousands of experts and government reviewers around the world.
The report stressed the half-degree difference was life-changing. Keeping the rise in temperature to 1.5C would mean sea levels by 2100 would be 10cm lower than if the warming was 2C, the likelihood of an Arctic Ocean free of sea ice in summer would be once a century rather than at least once a decade, and coral reefs would decline by between 70 and 90 percent instead of being virtually wiped out. For people, it would greatly reduce the risk of water shortages, food scarcity, and poverty related to climate change.
“The next few years are probably the most important in our history,” Debra Roberts, co-chair of the IPCC Working Group II, said in a statement marking the report’s release.
“The report shows that we only have the slimmest of opportunities remaining to avoid unthinkable damage to the climate system that supports life as we know it,” Amjad Abdulla, an IPCC board member and chief negotiator for the alliance of small island states, told the Reuters news agency.
To contain warming at 1.5C, man-made global net CO2 emissions would need to fall by about 45 percent by 2030 from 2010 levels and reach “net zero” by mid-century, the report said. Any additional emissions would require the removal of CO2 from the air.
The summary backed the use of carbon pricing and said governments needed to make a decisive shift towards renewable energy. At least 70 percent of electricity supply will need to come from renewables by 2050 to stay within the 1.5C limit, compared with about 25 percent now.
Using carbon capture and storage (CCS) technology, the share of gas-fired power would need to be cut to eight percent and coal to between zero and two percent. There was no mention of oil in this context in the summary.
If the average global temperature temporarily exceeded 1.5C, additional carbon removal techniques would be required to return warming to below 1.5C by 2100.
But the report said some measures, such as planting forests, bioenergy use or capturing and storing CO2, remained unproven on a large scale and carried some risks.
The Paris Agreement was adopted by 195 countries at the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change in December 2015, and designed to strengthen the global response to the threat of climate change. But Monday’s report comes amid a reactionary political climate.
US President Donald Trump has questioned the science of man-made climate change (sometimes called “anthropogenic climate change”) and vowed to withdraw the US, the world’s second-largest emitter of greenhouse gases after China, from the agreement.