Detection and attribution of anthropogenic climate change impacts

Abstract

Human-influenced climate change is an observed phenomenon affecting physical and biological systems across the globe. The majority of observed impacts are related to temperature changes and are located in the northern high-and midlatitudes. However, new evidence is emerging that demonstrates that impacts are related to precipitation changes as well as temperature, and that climate change is impacting systems and sectors beyond the Northern Hemisphere. In this paper, we highlight some of this new evidence-focusing on regions and sectors that the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4) noted as under-represented-in the context of observed climate change impacts, direct and indirect drivers of change (including carbon dioxide itself), and methods of detection. We also present methods and studies attributing observed impacts to anthropogenic forcing. We argue that the expansion of methods of detection (in terms of a broader array of climate variables and data sources, inclusion of the major modes of climate variability, and incorporation of other drivers of change) is key to discerning the climate sensitivities of sectors and systems in regions where the impacts of climate change currently remain elusive. Attributing such changes to human forcing of the climate system, where possible, is important for development of effective mitigation and adaptation. Current challenges in documenting adaptation and the role of indigenous knowledge in detection and attribution are described. climate itself. 1,2 Here, we focus on climate change impacts-a topic of major concern-and the issues arising from the detection and attribution of these impacts. These issues include consideration of multiple drivers of change, new types of evidence that have emerged since the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4), 3 and attribution of climate change impacts specifically to anthropogenic forcing. This paper presents an overview of the detection and attribution of climate change impacts, including how climate variables and non-climate factors affect physical and biological systems, methods of detection of observed changes, and the attribution of changes to anthropogenic climate forcing. We then present a summary of observed impacts and new evidence with a focus on the tropics and marine systems, which have Volume 4,

Assessing the observed impact of anthropogenic climate change

“…Most of the investigations informing the AR5 assessment were quantitative, but the development of that list was based on qualitative assessment and included a wide range of sources. That approach has pioneered outreach and allowed for the inclusion of impact categories that were not formally assessed in earlier reports, consistent with recommendations in the literature 22 . However it is subject to issues with expert elicitation, such as limited transparency and the difficulty of calibration.…”

Ecology and Management of Weeds in a Changing Climate

“…Thus, efforts to account for an array of potential climate variables affected by global climate change are vital and such efforts have been underrepresented in the literature to date [119]. More variable precipitation, particularly, when accompanied by warmer temperatures, will likely lead to increased drought; some studies have addressed the potential impact of such conditions on plant life, with once again weeds expected to fare better than native plants or crop plants [120][121][122].…”

A review of the biophysical impacts of climate change in three hotspot regions in Africa and Asia

“…Physical and biological systems can be affected by both climate and non-climate drivers (Rosenzweig and Neofotis 2013). A common link in all three hotspot areas is the manner in which climate and non-climate drivers interact to generate pressures and impacts on these different environments with consequent impacts for communities and their livelihoods.…”