The first installment  of the Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report (AR5)—released in September—confirmed  the overwhelming scientific consensus that the world is warming, largely due to human activities. The Working Group II (WGII) report , released today, takes this finding a step further : Not only is climate change happening, but every continent on earth is now experiencing its impacts.
Four major takeaways from the report showcase the impacts we’re already seeing, as well as those projected to occur if the world continues to warm. And more importantly, they reveal a critical message: As John P. Holdren, director of the White House Office of Science and Technology Policy, put it , the report “underscores the need for immediate action in order to avoid the most severe impacts of climate change.”
1) Climate change now affects every part of the planet.
The impacts of climate change are already occurring, and occurring everywhere. While the IPCC’s last report (AR4)—released seven years ago—showed that effects of regional climate change were “emerging ,” this latest report shows that observed impacts of climate change are now “widespread and consequential,” impacting both natural and human systems “on all continents and across the oceans.”
For example, the report finds that climate change has already led to:
- More negative than positive impacts to crops, such as wheat and maize;
- Coral bleaching and species range shifts;
- Higher risks posed by extreme events such as heat waves and coastal flooding; and
- Increased tree deaths in various regions.
2) Climate change will increase the frequency and severity of extreme weather.
The number of annual extreme weather and climate events has been gradually increasing  globally since the 1980s. In 2013 alone, the world saw 41 weather disasters  that each caused more than $1 billion worth of damages. The IPCC finds that unabated climate change will cause heat waves, extreme precipitation, coastal flooding, and other extreme events to intensify and become more frequent, creating significant risks for communities around the world. For example, in a warmer world we will likely see:
- Increased extreme precipitation events year-round in northern Europe;
- Cities like Mumbai, Miami, and Shanghai will have some of the largest amounts of assets exposed to coastal flooding under conditions where sea level rises by 0.5 meters; and
- Increased heat waves in northern Africa, a region that is already experiencing significant heat waves (e.g. between 1989-2009, northwestern Sahara experienced 40-50 heat wave days per year).
3) Meeting the scale of the challenge requires adaptation and mitigation.
Many communities and ecosystems around the globe are already experiencing the impacts of climate change, and given historical and current emissions, we’re locked in for additional warming. Consequently, we’ll need to build our capacity to adapt to climate change impacts. Adaptation is especially critical for the most vulnerable populations, such as those in low-latitudes and less developed areas, as well as communities whose livelihoods are strongly dependent on natural resources. This is true for both developed and developing countries. In Southeast Florida, for example, communities are already preparing measures to address impacts of sea-level rise.
Yet adaptation alone cannot overcome all climate impacts. And at a certain point--as is already the case in many places around the world—impacts become too severe or costly to adapt to. That’s why overcoming the climate change challenge will also require significant mitigation efforts.
4) Rapid and steep reductions in greenhouse gas emissions can reduce risks and costs—and the timing matters.
Limiting average global temperature rise to 2 degrees Celsius —an internationally agreed-upon target —is still achievable, but only if countries act with urgency to significantly and rapidly reduce their emissions. Limiting warming to this level would prevent some of the many risks that become exponentially more severe the higher temperatures climb.
For example, according to the IPCC:
- With each degree of warming, renewable water resources are projected to decline by at least 20 percent for an additional 7 percent of the global population.
- With warming greater than 2°C, there is a high risk of abrupt and irreversible changes to the structure and function of ecosystems. The Amazon forest, for example, would become less dense in the face of increased drought and fires. This change would not only affect species and ecosystem services, but would lead to “substantial additional climate change” considering that trees sequester significant amounts of carbon dioxide. Further, with this amount of warming, the oceans will become less efficient at absorbing CO2, which would cause additional warming and amplify impacts.
- If global temperatures rise more than 4°C – and there is a 20 percent chance  of exceeding this level by 2100 even if we implement existing emissions-reduction commitments -- there is high confidence that we could witness adverse impacts on agricultural production worldwide, extensive impacts to ecosystems, and increased risks of species extinction.
Reining in emissions now would not only prevent many of these escalating impacts, it would prevent costly economic impacts. The report states that losses increase with greater warming.
Perhaps most importantly, the report points out that what is done (or not done) to reduce emissions today will have an impact for decades to come and throughout the 21st century. If rapid reductions are not undertaken now, we will commit ourselves to levels of warming that will require radical and costly changes in the future to manage devastating impacts.
A Need for Immediate Climate Action
We’re already living in a different world due to the global average temperature increase of only 0.8 degrees Celsius that’s occurred since the Industrial Revolution. The latest IPCC report provides a picture of what the world will look like in the not-too-distant future should emissions continue unabated—and it’s not pretty.
We have an opportunity today to choose our future – for both limiting the worst of climate change impacts and for increasing our capacity to contend with them. We know  what levels of mitigation and adaptation are needed to limit and adapt to temperature rise—and we now know some of the impacts and costs of runaway warming. The message from the IPCC report is clear: The world’s communities, ecosystems, and economies can’t afford inaction.
- LEARN MORE: Read a response  from WRI's president, Dr. Andrew Steer, to the IPCC report.