Professor Valérie Masson-Delmotte:

I thank the joint committee for the invitation and giving us the opportunity to share the key findings of the IPCC special report on global warming of 1.5° Celsius. I will begin by highlighting the four main messages of the report, which are that climate change is already affecting people, ecosystems and livelihoods all around the world; limiting warming to 1.5° Celsius is not impossible but would require unprecedented transitions in all aspects of society; there are clear benefits to keeping warming to 1.5° Celsius compared with 2° Celsius or higher; and limiting global warming to 1.5° Celsius can go hand in hand with other world goals such as achieving sustainable development and eradicating poverty.

The report is the outcome of the collective work of 91 authors from 40 countries who have assessed new knowledge based on 6,000 publications. The successive drafts of the report received more than 42,000 review comments from more than 1,000 expert reviewers.

Since pre-industrial times - the end of the 19th century with regard to temperature - human activities have caused approximately 1° Celsius of global warming. We are already seeing the consequences of this through, for instance, rising sea levels and more extreme weather. At the current rate of warming of 0.2° Celsius per decade, the global mean surface temperature will reach an increase of 1.5° Celsius in the climate sense, averaged over 30 years, between 2030 and 2050. Although past emissions will continue to cause changes in the climate system and rises in sea levels, they alone will not cause global warming of 1.5° Celsius. Thus, limiting warming to 1.5° Celsius is not geophysically impossible. It will depend on emissions from now on.

I will discuss the differences between global warming of 1.5° Celsius and 2° Celsius for climate-related risks. Climate models project robust differences in regional climate characteristics between global warming of 1° Celsius, 1.5° Celsius and 2° Celsius above pre-industrial levels. They differences include the level of warming in various land and ocean regions, hot extremes, heavy rainfall in several regions and the probability of drought in some regions. Sea levels are projected to increase. Limiting global warming to 1.5° Celsius compared to 2° Celsius would reduce the rate of sea level rise by approximately 10 cm by the end of the century. That would mean that fewer people would be exposed to the consequences of rising seas and that there would be more time for adaptation.

Limiting global warming to 1.5° Celsius compared to 2° Celsius would also reduce the transformation and degradation of marine and terrestrial ecosystems and the risk of irreversible loss of biodiversity. It would imply smaller reductions in yields of key cereals, including maize, rice and wheat, and lower risks for fisheries and associated livelihoods, especially tropical fisheries. It would also reduce the percentage of the global population exposed to water shortages.

Climate-related risks are disproportionately higher for some regions, particularly dry land regions, small island developing states, the least developed countries and the Arctic region. There is a close link between development and climate-related risks and limiting warming to 1.5° Celsius compared to 2° Celsius would reduce the number of people exposed to climate-related risks and susceptibility to poverty by up to several hundred million by 2050.

Our report shows clearly that limiting global warming to 1.5° Celsius compared to 2° Celsius is associated with lower climate-related risks for food and water security, health, human security, livelihoods and economic growth. Our assessment highlights the need for adaptation, even to a small amount of warming such as 1.5° Celsius at a global scale, and the fact that there is a wide range of adaptation options that can reduce climate risks. However, there are knowledge gaps associated with the co-benefits, costs and limits of adaptation. To sum up, each 0.5° Celsius matters.

What emissions pathways and systems transitions are consistent with limiting global warming to 1.5° Celsius? If we want to limit global warming to 1.5° Celsius, global emissions of carbon dioxide need to fall by about half by 2030 and reach a net figure of zero by approximately 2050. For the purposes of comparison, limiting warming to 2° Celsius implies reducing emissions by around 20% by 2030 and reaching a net figure of zero by 2075. Mitigation pathways also imply deep reductions in other emissions of substances that lead to warming such as methane and black carbon by 35% or more by 2050. Reducing these non-CO2 emissions has direct and immediate benefits for air quality and health.

Limiting global warming to 1.5° Celsius is not impossible, but it implies rapid changes on an unprecedented scale in energy, land, urban, infrastructure and industrial systems. It means deep emissions reductions in all sectors, a steep decline in coal usage, the use of a wide range of technologies, behavioural changes on the demand side and an increase by a factor of five in investment in low-carbon energy and energy efficiency measures by 2050.

Rapid progress is being made in some areas, notably renewable energy. There is clearly a need to pick up this rate of progress in other sectors such as transport and land management.

Pathways also show that to limit global warming to 1.5° Celsius, we would need to start eliminating carbon dioxide from the atmosphere during the 21st century. Methods for doing this include land management, for instance, afforestation and reforestation; restoration of degraded ecosystems; agricultural practices linked with biochar and soil carbon sequestration; bioenergy combined with carbon dioxide capture and storage; and other approaches that are at the very early stages of research. Carbon dioxide removal on a large scale, for instance, with bioenergy, would have implications for food security, ecosystems and biodiversity through additional pressures on land.

Pledges made by governments under the Paris Agreement within the last three years are clearly not enough to keep global warming below 1.5° Celsius, even with ambitious and very challenging efforts after 2030. These pledges put us on track for 3° Celsius or more of warming if there is no increase in ambition. If we want to avoid overshooting 1.5° Celsius, or reliance on carbon dioxide removal later, carbon dioxide emissions would need to decline substantially on a global scale before 2030. To summarise, with 42 billion tonnes of CO2 emitted each year, each year matters.

What is the interplay with sustainable development and efforts to eradicate poverty? Climate change impacts and how we respond to them are closely linked with sustainable development. Our report shows clearly that each option and pathway has different synergies and trade-offs with other sustainable development goals. As part of limiting global warming to 1.5° Celsius, the report shows that it is a mix of measures to adapt to a changing climate and options to reduce emissions which, if carefully selected within each community, have benefits in meeting sustainable development goals. This reflects the notion of ethical and fair transitions. We also show that pathways with low energy demand, low material consumption and low carbon food carry the highest co-benefits, including for public health. Feasibility requires key ingredients - co-operation, governance, innovation and mobilisation of finance.

Each half degree matters; each year matters; and each choice matters. Limiting global warming to 1.5° Celsius is not impossible, but the political will to accelerate transitions is key. I thank committee members for their attention.