The Intergovernmental Panel on Climate Change (IPCC) is a United-Nations sponsored consortium of climate scientists working to analyze and summarize the extent and effects of climate change on our planet. IPCC reports are summaries that bring together thousands of disparate studies, but they are too long and complex for the layperson, even one with a strong interest in climate change. Here is a brief overview of the IPCC Assessment Report 5, which came out in the fall of 2014. The The full report contains data and projections judged on a scale from very low to very high confidence, but this summary discusses only findings with high or very high confidence.
Since the fourth report, in 2007, the number of climate-related publications has doubled, with a growing consensus that widespread, consequential changes are coming and that human activity is exacerbating natural climate change. The report lays out a list of changes we have already seen, such as coastal flooding and increased storm surges caused by sea-level rise, drought and floods exacerbated by increasingly variable precipitation and rising temperatures, disasters occurring in new areas, and loss of sea ice and ocean acidification linked to rising ocean temperatures. Climate change is not yet the largest killer of species, but as the Earth warms and ecological zones shift polewards, terrestrial and aquatic plants and animals follow. Polar ecosystems are disappearing, and the arctic species must either adapt to warmer conditions or die. Glaciers and permafrost are retreating on every continent. Glacier-fed rivers are swollen while those dependent on precipitation are drying up. Forests bloom earlier in the spring, but dry out and feed more fires each year. The coral and seaflora in the Pacific and Caribbean are declining. These changes are beyond what can be attributed to pollution, over-use by humans, or annual fluctuations.
Knowing for certain what the future holds is impossible, but the IPCC report uses the best data and models available today to estimate the likelihood of future climate-related changes. The effects are multifaceted and depend greatly on one’s location and socioeconomic status: the more marginal one’s status, the more vulnerable he or she is. Although economic and social factors affect one’s life more than climate change today, the indirect effects on our health, security, and livelihoods are growing. Most of us depend on industrial agriculture, and while increased temperatures and climate variability decrease crop yields, increased levels of CO2 stimulate growth; to survive, we must create resilient agricultural systems. Food insecurity, coastal and inland flooding, drought, loss of marine and terrestrial biodiversity, and the compounding of interrelated problems are highly likely to occur. The two primary models used in this report estimate an additional 1-4°C rise in global temperatures by 2100, which is a narrower range than the last report.
The IPCC projects that North America will suffer from climate-induced drought exacerbated by irrigation and urban overuse. Although northern farms will see increased yields, overall agricultural output will decline because of the increased heat stifling southern crops. The IPCC lists North America’s water-resources, transportation infrastructure, and coastal areas as the most vulnerable to current changes. Rural and urban adaptations are necessary to mitigate both the certain and potential effects of climate change. Specifically, improved infrastructure, effective warning systems, sustainable cooling, urban planning, and a more resilient healthcare infrastructure are needed.
Governments across the world are responding to climate change, but most are focused on risk management instead of addressing the root cause. The report states with very high confidence that damage from climate change is unavoidable, but the extent of that risk could be mitigated by a reduction of greenhouse emissions. It does not define a single “tipping point” after which we would suffer systemic collapse but notes that reducing greenhouse emissions would reduce the likelihood that we would reach that point.
It is difficult to stay positive in the face of overwhelming data and predictions. We are each responsible for our own actions, and while it seems difficult to single-handedly change systemic problems, we can make a difference. Speak out in social situations when somebody mischaracterizes climate science. Lead by example and discuss changes you have made in your own life to reduce your carbon footprint. If you are in a leadership position, use facts to help make proactive decisions for the future. Get familiar with the section of the report that pertains to you.
Note: I was only able to scratch the surface of the report, which is over 2500 pages long. If you are interested in reading more, the IPCC has written a 44-page “Summary for Policymakers” in plain, although dry, English.