Climate impacts and adaptations are just some of the topics Katharine Mach, an associate professor at the University of Miami's Rosenstiel School of Marine and Atmospheric Science, helped address as a lead author on the Intergovernmental Panel on Climate Change Sixth Assessment Report.
It was a meeting in Addis Ababa five years ago that laid the foundation. A group of scientists assembled by the United Nations had gathered in the capital of Ethiopia to draft the outline of a landmark report that would assess the state of the world's climate.
That initial forum of the UN's Intergovernmental Panel on Climate Change (IPCC) informed three different working groups, each charged with authoring a section of the IPCC's Sixth Assessment Report. And by August of 2021, Working Group I had completed and released its chapter on the physical science of climate change, warning that humans have altered the environment at unprecedented levels and that the window to prevent the most catastrophic effects of greenhouse gas emissions is rapidly closing.
Now, Working Group II, which includes a University of Miami researcher in environmental science and policy, has issued its contribution to the nearly 4,000-page report. In their assessment, unveiled Feb. 28 during a virtual press conference, the authors not only reaffirm that climate change is widespread, rapid, and intensifying, they also address its impacts, the efforts to adapt to it, and the groups of people who are most vulnerable to its effects.
"If we were to jump back decades to when these reports started, climate change was mostly a hypothetical—something that we, as a global community, could avoid," said Katharine Mach, associate professor at the University's Rosenstiel School of Marine and Atmospheric Science and a lead author for the IPCC's Working Group II.
"But then as we moved forward, the evolution was that warming is unambiguously occurring," she said. "And certainly, when the Fifth Assessment Report came out in 2014, it was at that point we could detect and attribute impacts of climate change on every single continent, not just in terms of the change in climate, but also how it's affecting agriculture and livelihoods and health."
The Earth's changing climate has led to sea level rise, drought, an increase in tropical cyclone activity, and more heatwaves, adversely affecting ecosystems, food security, water resources, human health, and infrastructure, the chapter penned by Working Group II reports.
Indigenous peoples and communities in low-lying coastal areas are often hardest hit by the impacts of climate change, the authors noted.
"Most underserved communities bear the brunt of the impacts that do occur. And that plays out within and across countries. So, that's a key component of the complexity of understanding the full distribution of impacts and responses," Mach said. "And then, the next part of the complexity that's a big step forward is recognizing that the responses that we take at this point are an unambiguous part of the climate issue. We are trying to actively reduce emissions. We're trying to figure out how to keep people safe. And these actions that we're taking constitute the new space of learning how to do this well."
While efforts aimed at adapting to climate change have ramped up significantly during the past eight years, the world is not adapting fast enough, and significant gaps exist between policies that are being implemented and what is needed, according to the assessment.
Closing those gaps will require governments, business, civil society, and individuals to act at a much faster rate than the current pace.
"The huge step forward is at this point, we can document globally the degree to which there's recognition and action happening to address climate impacts," Mach explained. "At the same time, we are making some progress with grappling with emission reductions. But the big question is, 'Is it enough?' "
Disaster-proofing energy plants and other critical infrastructure, improving health systems to reduce the impacts of climate-related risks, protecting and restoring natural forests, and safeguarding ecosystems are just some of the adaptation measures that can be taken, the assessment suggests.
The number of people worldwide who consider climate action a priority is growing, notes the first chapter, citing a survey that revealed almost two thirds of the people across 50 countries view climate change as an emergency, with the highest level of support for climate action coming from small developing states.
Mach's own Rosenstiel School research, which assesses climate change risks and response options to address increased flooding, extreme heat, wildfire, and other hazards, is closely related to the IPCC Sixth Assessment chapter on which she served as a lead author.
For Mach, working on the IPCC chapter to inform various groups of the current state of the world's climate "was one of the more rewarding aspects" of her work. She added that, because of the pandemic, her group mostly met virtually during the past two years.
Mach said that she believes several audiences will benefit from this latest IPCC report, from the media to world governments.
"But it's important to recognize that the U.S. and other high-income countries, in addition to having access to the IPCC report, also have national to local assessment processes working for them," she explained. "By contrast, for lower-income countries, there isn't necessarily a national, much less a local, climate assessment. So, in that regard, these IPCC reports are invaluable."
