“Abrupt Impacts of Climate Change”

Abrupt Impacts of Climate Change: Anticipating Surprises, now in final form from the National Academy of Sciences, differs from previous studies by focusing both on abrupt climate changes and on abrupt climate impacts that have the potential to severely affect the interconnected physical climate system, natural systems, and human systems. Abrupt Impacts of Climate Change contends that the threat of tipping points is real and serious, and that focused action is needed to better anticipate, prepare, and seek to limit the unavoidable damages from inevitable surprises.

Abrupt Impacts of Climate Change: Anticipating Surprises can be purchased in book form, downloaded free in PDF format, or read online.

Some key messages from the report:

• There is a new recognition that, in addition to abrupt changes in the climate system itself, steady climate change can cross thresholds that trigger abrupt changes in other physical, natural, and human systems.
• The report highlights two abrupt changes that are already underway, making these changes a primary concern for near-term societal decision making and a priority for research. First, warmer Arctic temperatures have caused a rapid decline in sea ice over the past decade, with potential impacts on the Arctic ecosystem and on Arctic shipping and resource extraction. Another abrupt change already underway is increased extinction pressure on plant and animal species; this gradual climate pressure, in combination with other sources of habitat loss, degradation, and over-exploitation, is already putting some species at greater risk of extinction.
• Large uncertainties about the likelihood of some potential abrupt changes highlight the need for expanded research and monitoring. For example, as climate warms, the destabilization of the West Antarctic Ice Sheet could raise sea level rapidly, with serious consequences for coastal communities.
• The committee believes that action is needed to develop an abrupt change early warning system. Such a system would be part of an overall risk management strategy, providing information for hazard identification and risk assessment. These data would help identify vulnerabilities to assist in tailoring risk mitigation and preparedness efforts and to ensure warnings result in appropriate protective actions, with the ultimate goal of preempting catastrophes.
• Abrupt climate changes and impacts present substantial risks to society and nature. Although there is still much to learn, to ignore the threat of abrupt change would lead to more costs, loss of life, suffering, and environmental degradation. The time is here to be serious about the threat of tipping points, so as to better anticipate and prepare ourselves for the inevitable surprises.

The National Research Council panel that wrote this report has done a valuable service in assessing and synthesizing the current state of knowledge about a range of climate change impacts that could occur ‘abruptly’, i.e., on timescales of years to a few decades. There remains considerable scientific uncertainty about the timing and consequences of various potential changes. The authors’ assessment of the relative likelihood of various changes and impacts could no doubt be the subject of debates in the science community. Nevertheless, we are already seeing dangerous abrupt climate change with the rate of Arctic warming and loss of sea ice, with the likelihood of disruptive impacts at lower latitudes. We face the prospect of greatly accelerated rates of species extinction due to multiple stresses including climate change.

All the more reason, then, at a time when research and observing system budgets are under constant pressure, to support a stepped up effort in monitoring and scientific research as part of a societal risk assessment and management strategy. Monitoring and research on abrupt climate change issues are an essential component of society’s intelligence capability for understanding the impact of human activities on the Earth system, and for informing policies to alter the trajectory of human action onto less destructive paths.

The report’s call for an Abrupt Change Early Warning System, “to assist in tailoring risk mitigation and preparedness efforts and to ensure warnings result in appropriate protective actions,” raises issues of connecting climate change research with policymaking. We have long supported a strong role for climate change impacts assessments, and have argued for the importance of adaptive preparedness policymaking and action at all levels of government and in the private sector to enhance community resilience to inevitable consequences of global climatic disruption. At the same time, unless there is an expedited, dramatic change in the trajectory of steadily growing worldwide emissions of greenhouse gases, and the steadily increasing atmospheric concentration of carbon dioxide, the impacts of climatic disruption on societies and ecosystems could overwhelm the capabilities of preparedness.

Mitigation — emissions reduction — and adaptive preparedness are both essential; neither can be shortchanged. Climate policy advocacy should treat as an integrated whole the need for continuous climate change monitoring, strong support for scientific research, ongoing scientifically based risk assessments, and what an earlier National Academy study termed ‘iterative risk management’ policy — including both an expedited phase-out of fossil fuels and decarbonizing the energy system, and stepped up preparedness planning and action to develop climate-resilient communities. There is no good reason why all of this can’t be accomplished in tandem. What we are learning from the science community about the threat of abrupt climate changes and abrupt impacts of climatic disruption should be taken as yet another warning that there is no reasonable alternative.