Climate variability, abrupt changes and tipping points

Climate variability refers to natural variations in climate patterns over interannual to multidecadal/centennial timescales, extending beyond individual weather events and driven by both internal and external factors. Understanding the interplay between climate variability and climate warming is crucial for attributing observed changes and distinguishing natural variations from human-induced climate warming. Moreover, gaining deeper insight into the drivers of climate variability modes and their climatic impacts is essential for improving climate predictions. Building on the understanding of climate variability and climate change, evidence from modelling, observations, biophysical theories, and paleo-records suggests some of the Earth’s systems can exhibit tipping points and abrupt changes.

A climate tipping point is defined as a critical threshold that, once crossed, results in significant, rapid and frequently irreversible changes within the climate system, and has far-reaching implications for the climate, ecosystems and humans. In some cases, passing one tipping point can influence the likelihood of tipping in other interconnected systems and trigger cascading effects, where one tipping event sets off a chain reaction. Early indicators of a tipping point could be observable before the transition occurs. For some types of tipping points, theory suggests that subtle changes in the statistical properties of monitoring data, known as early warning signals, can provide advance notice of an event.

Objectives

The main objective of this research area is to advance the understanding of climate variability and its interplay with climate change, as well as investigating tipping points and associated abrupt changes. This includes conducting in-depth analysis of the underlying processes driving these phenomena, by using novel methods, and performing new climate model simulations. The objective will be achieved through the following approaches and key focus areas:

• Understanding climate variability and the physical processes that shape climate patterns across regional and global scales, and mapping climate variability in the context of global warming.
• Analyzing Arctic climate and sea ice, and their impacts on lower-latitude climates.
• Assessing the likelihood of occurrence and early warning indicators of tipping points and associated abrupt changes in the North Atlantic Ocean (e.g. AMOC) and Arctic (e.g. sea ice), as well as their interactions with other tipping points in the Earth system and the potential for cascading tipping events.
• Investigating uncertainty in climate models, with a view to improving predictions of climate variability, tipping points, and associated impacts.
• Assessing the regional and global impacts of tipping points and rapid climate changes, with a focus on their socio-economic effects on regions vulnerable to such shifts.