Met Office position on geoengineering research

Summary

• Geoengineering is the deliberate large-scale manipulation of climate. Geoengineering technologies are increasingly part of conversations about the appropriate global response to climate change and plans to meet the goals of the Paris Agreement, alongside reductions in greenhouse gas emissions.
• Current research suggests that, while such schemes could be effective in reducing climate change, they could also have significant drawbacks. The type and scale of the drawbacks depend on the type of geoengineering.
• Impartial research is needed to further understand geoengineering, alongside mitigation measures, to ensure any future discussion of options to tackle climate change is based on the best available evidence and information. The Met Office has a role to play in undertaking this impartial research.
• The Met Office does not advocate any particular approach to mitigation. It will work with UK and international research partners to help deliver the science needed to underpin discussions on this area because the science is essential to determine the risks, impacts and opportunities.
• The Met Office’s contribution will be based on simulations using climate models and we do not advocate or provide context for real-world physical experiments.

What is geoengineering?

Geoengineering describes interventions and technologies which could be deployed to alter aspects of the global climate system to help tackle some aspects of global warming. These methods are increasingly debated as people around the world consider how best to minimise the risks of climate change.

There are two key categories that fall under the term ‘geoengineering’:

• Greenhouse Gas Removal (GGR) is the use of natural and artificial means to take greenhouse gases from the atmosphere and sequester them for an extended period of time. This could include planting trees or encouraging marine phytoplankton growth, through to technology which can chemically remove CO₂ from the atmosphere or employing a process known as bioenergy carbon capture and storage (BECCS) (where biomass is burnt for energy and the carbon dioxide captured).
• Solar Radiation Modification (SRM) is use of technologies to reflect some of the Sun’s energy that reaches Earth back into space, thereby reducing the Earth’s temperature to offset global warming. This could include strategies to brighten clouds over the ocean or injecting aerosols high into the atmosphere.

Why is geoengineering being discussed?

In 2015 global governments signed the Paris Agreement, whose goal is to keep global temperature rise to well below 2°C and to pursue effects to limit the increase to 1.5°C, compared to pre-industrial levels. Rapid and deep cuts in global greenhouse gas emissions are essential in order to meet this goal. Research shows that the few pathways that exist to 1.5°C without some GGR require very early and rapid reductions in emissions which many suggest will not be feasible. More controversially, others have suggested SRM techniques should be considered as one option to help meet the goal either as a long-term solution or a shorter-term option to allow for GGR capacity to be expanded.

What does the current research show?

Understanding the full implications of any geoengineering technology remains complex and more research is needed to fully understand the potential benefits and drawbacks.

Greenhouse Gas Removal (GGR) strategies

Research suggests these could be a vital tool in reducing global greenhouse gas emissions to help meet the Paris Agreement and are an integral component of pathways to net-zero emissions. Questions remain over the amount of GGR needed, the way technologies are employed globally, the length of time greenhouse gases remain sequestered for and what the optimal balance of different techniques may be in order to minimise potential drawbacks. For example, research shows extensive growth of crops for BECCS could reduce the amount of land available for food production – posing a risk to food security.

Solar Radiation Modification (SRM)

This remains a much more controversial area where the science is still at an early stage. Available research using models suggests these techniques could be effective at reducing warming overall and reducing hazardous climate extremes, but there could be complex and significant drawbacks. For example, various research papers have highlighted that if deployed in a non-optimal way, SRM techniques could increase drought risk in the Amazon and Sahel region, increase North Atlantic hurricane activity, and affect winter rainfall over Europe. In addition, it is likely there would be rapid climate change if SRM were terminated in an uncontrolled manner.

Much more research is needed to understand all the potential benefits and drawbacks associated with these different techniques to ensure any debate in this area is based on robust evidence.

What is the Met Office’s position on geoengineering?

The Met Office does not advocate any particular approach to mitigation, but research shows that deep and rapid cuts in emissions will be challenging to achieve on a global basis. Therefore, geoengineering technologies are increasingly part of global discussions to determine how to meet the Paris Agreement goal of limiting global warming to well below 2°C, preferably to 1.5°C, to significantly reduce the risks and impacts of climate change.

Currently much more information is needed to ensure any discussions are based on a robust and broad range of evidence. It is therefore important that impartial science is carried out which looks at the effectiveness, trade-offs and side-effects of all types of mitigation options – including geoengineering. As a major contributor to global climate science, the Met Office has a key role to play in this area alongside its research partners across the UK and the world. The Met Office’s contribution will be based on simulations using climate models and we do not advocate or provide context for real-world physical experiments.