By Louis Verchot, International Center for Tropical Agriculture
On 8 October, the Intergovernmental Panel on Climate Change (IPCC) issued a report that assesses the state of science on the benefits of limiting warming to 1.5 degrees Celsius and compares this to the current target of 2 degrees Celsius that has been widely accepted in scientific and policy circles. It makes a strong case for limiting warming to 1.5 degrees.
The key finding of the report that is not being covered enough in the press, however, is that all of the pathways that the IPCC analyzed for achieving the 1.5-degree target require significant carbon dioxide reductions, or CDR for short. The reality is that there will always be some carbon dioxide or other greenhouse gas emissions, so these need to be offset by removals somewhere. Forests – and their protection – play a crucial role in this mitigation, and a role that is largely being overlooked.
At an average warmer temperature of 1.5 degrees, there will be significant differences in extreme weather events compared to a 2-degree world: heat waves will not be as strong; increases in heavy precipitation will be less damaging, particularly in mountainous regions; droughts will not be as severe; ocean acidification will be tempered.
To achieve this lower target, the report calls for achieving net zero carbon dioxide emissions in the next 12 years. Even if this could be achieved, temperatures remaining below 1.5 degrees would depend on how the earth system responds.
If we are not successful at cutting fossil fuel emissions, CDR will be even more important to stabilizing the climate system. And if we overshoot the 1.5-degree target, CDR will be essential for returning the climate system to the 1.5-degree conditions.
What is CDR? There are basically two approaches to removing carbon dioxide from the atmosphere. Carbon capture and storage (CCS) uses scrubbers – equipment that can separate out carbon dioxide from air. This carbon dioxide is then liquefied and pumped into geological storage in depleted oil and gas fields or in deep saline aquifers. The second approach is biosequestration, which is the removal and storage of carbon dioxide from the atmosphere through biological processes, like afforestation and reforestation, increasing soil organic matter and restoring degraded ecosystems.
CCS approaches can be deployed to remove carbon dioxide from ambient air in what is called direct air capture. CCS scrubbers can also be attached to power plants, which can reduce emissions by up to an estimated 90 percent. If CCS technology is combined with bioenergy production, referred to as BECCS, the technology has the potential to create what are called ‘negative emissions.’ In other words, producing energy in a BECCS system would result in net carbon dioxide removal from the atmosphere.
The major risk raised by the report is that CDR has never been deployed at scale, and reliance on unproven approaches is an uncertain path to limiting warming. CDR is needed less in pathways with particularly strong emphasis on energy efficiency and low demand. The scale and type of CDR deployment varies widely across 1.5 degree–consistent pathways analyzed in the report, with different consequences for achieving sustainable development objectives.
CCS technology has had a lot of problems getting a foothold in national and local programs to tackle climate change. Lack of government action, public concerns about the safety of storage and environmental impacts, low carbon prices, and lower costs of renewables have all contributed to the technology’s poor uptake.
Expanding afforestation and reforestation and enhancing forest sinks are also proving to be problematic. The slow progress of REDD+ initiatives, and recent increases in deforestation in Brazil, Colombia and the Democratic Republic of Congo indicate that there is still much to be done. Entrenched interests in deforestation and institutional resistance to change are among the major obstacles that need to be overcome.
Neither approach should be overlooked, but many people do not appreciate what forests are already doing for the climate change problem.
To raise awareness about this issue, a group of 40 scientists recently released a statement warning that the world’s governments are overlooking the role of forests in combating climate change risks. The scientists point out that the world’s forests contain more carbon than all of the world’s exploitable oil, gas and coal deposits. Therefore, avoiding forest carbon emissions is just as urgent as halting fossil fuel use.
The Global Carbon Project estimates that forests absorb about one-quarter of all anthropogenic emissions. The destruction of forests not only releases carbon dioxide into the atmosphere, but it also it reduces forests’ ability to absorb emissions. Protecting and restoring forests could achieve 18 percent of the emissions mitigation needed by 2030 to achieve the 1.5-degree limit.
Beyond the global effects on climate, tropical forests cool the air around them and affect local climates. They are important parts of regional hydrological cycles, pulling moisture out of the ground and releasing water vapor to the atmosphere, in turn regulating local and regional rainfall patterns. Cutting down tropical forests increases local surface temperatures by up to 3 degrees. These ‘climate regulation’ effects of tropical forests make their conservation essential to food and water security.
As the economist Herman Daly wrote in one of his books, “the economy is a wholly owned subsidiary of the environment, not the reverse.” Reduction and elimination of fossil fuel emissions in the coming decades is absolutely essential for achieving a stable climate and economic prosperity. But it is not enough.
The scientists’ statement closes with a simple message: “Our planet’s future climate is inextricably tied to the future of its forests.”
Fateful effects of climate change could come sooner than expected