Attribution of extreme climate events to global climate change as a result of anthropogenic greenhouse gas emissions has become increasingly important. Extreme climate events arise at the intersection of natural climate variability and a forced response of the Earth system to anthropogenic greenhouse gas emissions, which may alter the frequency and severity of such events. Accounting for the effects of both natural climate variability and the forced response to anthropogenic climate change is thus central for the attribution.

Here, we investigate the reproducibility of probabilistic extreme event attribution results under more explicit representations of natural climate variability. We employ well-established methodologies deployed in statistical Earth System Model emulators to represent natural climate variability as informed from its spatio-temporal covariance structures. Two approaches towards representing natural climate variability are investigated: (1) where natural climate variability is treated as a single component; and (2) where natural climate variability is disentangled into its annual and seasonal components.

We showcase our approaches by attributing the 2022 Indo-Pakistani heatwave to human-induced climate change. We find that explicit representation of annual and seasonal natural climate variability increases the overall uncertainty in attribution results considerably compared to established approaches such as the World Weather Attribution Initiative. The increase in likelihood of such an event occurring as a result of global warming differs slightly between the approaches, mainly due to different assessments of the pre-industrial return periods.

Our approach that explicitly resolves annual and seasonal natural climate variability indicates a median increase in likelihood by a factor of 41 (95% range: 6-603). We find a robust signal of increased likelihood and intensification of the event with increasing global warming levels across all approaches. Compared to its present likelihood, under 1.5 °C (2 °C) of global near-surface air temperature increase relative to pre-industrial temperatures, the likelihood of the event would be between 2.2 to 2.5 times (8 to 9 times) higher.

We note that regardless of the different statistical approaches to represent natural variability, the outcomes on the conducted event attribution are similar, with minor differences mainly in the uncertainty ranges. Possible reasons for differences are evaluated, including limitations of the proposed approach for this type of application, as well as the specific aspects in which it can provide complementary information to established approaches.

Solar geoengineering: a note to inform discussions on physical climate impacts, risks and governance issues

With international efforts on climate action still not on track to limit warming to 1.5°C, technological fixes that aim to intentionally alter the Earth’s climate, such as solar geoengineering, might seem like appealing options for tackling global warming. But they come with questions in terms of feasibility, impacts and risks, governance and geopolitics, and who may or may not benefit.

Achieving net zero greenhouse gas emissions critical to limit climate tipping risks

Current climate policies are putting Earth on a path to a high risk of triggering climatic tipping points – even if temperatures return to below 1.5°C of global warming after a period of overshoot. A new study finds that the risk of crossing these thresholds increases with every additional 0.1 °C of overshoot above 1.5 °C and strongly accelerates above 2.0 °C. These risks can be minimised if stringent emissions reductions are taken in the next decade, and net zero greenhouse gas emissions are met and maintained.

Evaluating the near and long-term role of carbon dioxide removal in meeting global climate objectives

For 1.5°C pathways with limited overshoot, most of the mitigation between now and 2030 should come from emissions reductions (70%), with reductions from cutting non-CO2 emissions (20%) and land-based carbon dioxide removals such as afforestation and preventing deforestation (10%) making up the remainder.

A review of loss and damage in the Caribbean (1994 to 2024)

Loss and damage from climate change has been the lived reality of Caribbean small island developing states (SIDS) for decades. Despite efforts to adapt, it is reversing development gains, leaving lasting financial stress, and causing irreparable damage, including the loss of cultural heritage. This report is the first to provide a systematic overview of how Caribbean countries are framing and reporting on loss and damage.

Heavy precipitation hitting vulnerable communities in the UAE and Oman becoming an increasing threat as the climate warms

Researchers have assessed the extent human-induced climate change altered the likelihood and intensity of the weather conditions that caused the flooding in the United Arab Emirates and the northern parts of Oman in April 14–15 2024. The region was hit by exceptionally heavy rainfall causing massive disruption in infrastructure and public life in the area and leading to at least 20 fatalities in Oman and four in the UAE.

About us

Decarbonisation targets and 1.5℃ pathways

Comment

Representing natural climate variability in an event attribution context: Indo-Pakistani heatwave of 2022

Publications

The role of northern forests in limiting warming to 1.5°C

Rapid urbanisation and climate change key drivers of dramatic flood impacts in Nepal

Seasonal forecast of two-metre temperature and precipitation in Tanzania: A hybrid cluster and point-by-point machine learning approach

Overconfidence in climate overshoot

Solar geoengineering: a note to inform discussions on physical climate impacts, risks and governance issues

How can event attribution science underpin financial decisions on Loss and Damage?

Achieving net zero greenhouse gas emissions critical to limit climate tipping risks

Evaluating the near and long-term role of carbon dioxide removal in meeting global climate objectives

Increasing April-May rainfall, El Niño and high vulnerability behind deadly flooding in Afghanistan, Pakistan and Iran

A review of loss and damage in the Caribbean (1994 to 2024)

Earth Virtualisation Engines (EVE)

Heavy precipitation hitting vulnerable communities in the UAE and Oman becoming an increasing threat as the climate warms