Emerging Climate Risks and what will it take to limit global warming to 2.0°C?

The science challenges and gaps for transitioning to a low carbon society and limiting warming well below 2°C - as well as the actions needed.

Emerging Climate Risks and what will it take to limit global warming to 2.0°C?

This article is part of the ISC’s Transform21 series, which will explore the state of knowledge and action, five years on from the Paris Agreement and in a pivotal year for action on sustainable development. This piece was first shared by the World Climate Research Programme (WCRP).

A joint session was hosted by WCRP, IPCC and Future Earth at COP26 to discuss risks and consequences of breaching 1.5°C warming, and possible transformation pathways that can guide decision makers and stakeholders. All speakers were asked to identify up to five priority actions and/or challenges for our research community regarding the transition to a low carbon society and limiting warming to well below 2°C. This is a summary of these science challenges, science gaps, and some of the actions needed.

Watch the session here:

1.  Overview

Anthropogenic climate change brings many significant challenges and risks that affect almost all aspects of life on Earth. Droughts, heavy rain and flooding, heatwaves, extreme fire weather and coastal inundation are already increasing in frequency and intensity. The scale of these climate changes and the resulting risks and impacts grow with every additional increment of warming, affecting millions of people around the world, especially the poorest with risks to food and water security; ecosystem health and biodiversity that threaten several of the Sustainable Development Goals (SDGs).

To reduce such threats, the COP21 Paris Agreement aimed to limit global warming to well below 2°C above pre- industrial temperatures and to pursue efforts to limit warming to 1.5°C. Given the cumulative effect of CO2 emissions on global warming, and the small remaining carbon budget, this requires a dramatic reduction of emissions of all anthropogenic climate forcers, especially fossil CO2, over the next decade. Eventually, net zero greenhouse gas emissions by 2050 are needed to reach this goal.

Given current policies, and updated nationally determined contributions, it appears increasingly likely that the remaining carbon budget associated with a 50 or 67% chance to limit warming at 1.5°C will be exhausted in the 2030s, leading to an overshoot of the 1.5°C goal. Any delay in emissions reduction is committing the planet to even greater global warming and greater risk of more intense and frequent weather and climate extremes. Staying below 2.0°C requires an unprecedented transformation, including increased reduction of residual CO2 emissions and sustainable approaches to removing excess CO2 from the atmosphere. Negative emission technologies to remove carbon dioxide will be needed but questions remain about the scale required, feasibility, costs, as well as trade-offs, especially when related to land based options.

2.  Key Scientific Challenges

2.1 Improved process understanding of the entire Earth system – across all scales and including human (social) systems and climate risks

2.2 Improved information about the climate and Earth System

2.3 Building and strengthening bridges

3.  Risk has a scale: what science is needed to support actions at the decision-scale?

There is ample robust climate information at the global and regional scale but weak actions. Yet, at the local scales where impacts are experienced, there is generally a willingness to act even if robust climate information is limited. Tensions therefore arise between where resource decisions are made and where the impacts occur.

Several of the priority actions to address this and ensure that climate science is effective in enabling policies and decisions to manage local-scale climate risk and reduce its impacts on vulnerable communities and regions around the world, are within the scope of WCRP’s Regional Information for Society Core Project and My Climate Risk Lighthouse Activity. They include:

4.  What is needed to accelerate progress and action?

5.  The path to net zero – science and technology needs

To reduce climate risk and comply with the ambitious goals agreed to under the 2015 Paris Agreement, CO2 emissions must fall to net zero by mid-century; yet the world is very slow in getting on track for this goal. Although many elements required for the transformation are already clear – such as rapid reduction in fossil fuel use and production, stopping deforestation and reducing emissions from land use – it is also clear that CO2 removal (CDR) technologies will be needed at scale to limit warming. For example, the 2018 IPCC Special Report on Global Warming of 1.5 °C shows that those 1.5°C pathways with limited overshoot, aiming to reduce the dependence on CDR, still remove a significant amount of CO2 from the atmosphere (specifically, 100 Gt CO2 cumulatively until 2100).

Comparing these pathways (to 1.5 or 2°C) to our current reality reveals a striking gap in innovation and policy, and in societal dialogue. Scaling the technologies and approaches to remove CO2 from the atmosphere raises questions like: Where should the biomass come from without jeopardizing other SDGs if bioenergy is to be significantly scaled-up? How permanently can CO2 be stored in forests, agricultural soils and other terrestrial and marine ecosystems given the impact of ongoing climate change on them? What can other approaches such as direct air capture, enhanced weathering, biochar, and other natural climate solutions, contribute to a more resilient portfolio of removal technologies that minimize risks to other SDGs? Such questions clearly show the urgent need for solutions to residual emissions and CO2 removal.

In the short term, innovation, funding and pilot projects are all required to catalyse the science and technology needed not just for emission and CDR technologies but also for robust and transparent methods of monitoring and verification. The latter is especially important to avert discrepancies between stated commitments and actual actions that will lead to a shortfall in the global emissions reductions needed to stabilise the climate. In the medium term, clear governance structures will be needed to address concerns about moral hazard. In the long term, a comprehensive carbon pricing architecture that considers just transition dimensions, can help to reward and finance carbon removal, while charging for the remaining carbon emissions.

Moreover, a lens that takes a broader view than just carbon will be needed, accompanied by a carbon-focused policy architecture with safeguards and regulation that ensures sustainability. Science must play a critically important role in filling the knowledge gaps with actionable knowledge.

You might also be interested in

Four considerations for accelerating progress on climate change at the science-policy interface

In the side event held by WCRP, Future Earth and the IPCC at COP26, ISC President Peter Gluckman called for a step change in science and science-funding in order to deliver actionable, solution-oriented knowledge, highlighting four concerns relevant to accelerating progress.

Photo by Sergey Pesterev on Unsplash.


Skip to content