Protecting critical resources like forests crucial to slowing climate change: United Nations

The new report emphasizes that reducing fossil fuels alone is not enough.

Land-surface temperatures have increased nearly twice as much as global average temperatures, the report said, as human activities on land have released more than 20% of global emissions.

Protecting forests that absorb carbon and reforming agricultural practices could play a large role, according to the report.

"Land plays an important role in the climate system," Jim Skea, co-chair of the Intergovernmental Panel on Climate Change, said in a press release.

"Agriculture, forestry and other types of land use account for 23% of human greenhouse gas emissions," he said. "At the same time natural land processes absorb carbon dioxide equivalent to almost a third of carbon dioxide emissions from fossil fuels and industry."

Zeke Hausfather, an analyst will the non-profit research group Berkeley Earth, said it's important to look at the impact of climate change on land separately from global averages because those affect people the most.

"The whole world has warmed by about 1.1 degrees Celsius, 2 degrees Fahrenheit, from the pre-industrial period, but if you look at the land areas they warm about 50% faster," he told ABC News, adding that the difference is partly because oceans have a greater capacity to absorb heat.

Berkeley Earth's analysis of land-surface temperatures over the last 250 years have found that those temperatures have increased about 1.5 degrees Celsius in the same time period, with about 0.9 degrees of that occurring in the last 50 years.

Frances Seymour, a senior fellow from the World Resources Institute whose work focuses on forests, said there's a circular relationship between climate change and the health of global land and forests because both release carbon dioxide and capture it.

Destroying forests actually releases carbon dioxide into the atmosphere, and those trees no longer can absorb additional CO2 that otherwise enters the atmosphere, she added.

"Deforestation is a significant part of the problem, but better management of the forests is an even bigger part of the solution," she said. "It's not just the carbon spewed into the air when a forest is converted into something else, it's that lost opportunity to keep that natural carbon-capture-and-storage factory up and running."

The report also emphasized that people in southern and eastern Asia, northern Africa and the Middle East likely will bear the brunt of the effects from continued depletion of vital water and land resources, according to the summary.

Hausfather said that while most of the focus in the U.S. tends to be on domestic impacts of climate change, countries that emit less greenhouse gas suffer the most as temperatures and sea levels rise.

"One of the big challenges of climate change is the many ways the people who are least responsible for climate change are the most affected," he said. "You can build a sea wall around Manhattan -- it's a lot harder to build one in Bangladesh."

Hausfather said warming in the Arctic or Alaska is a better indicator of the impacts of climate change on land, where, he said, some places have seen average temperatures increases as high as 3 or 4 degrees Celsius.

The National Oceanic and Atmospheric Administration announced this week said the temperatures in Alaska this July were the highest on record, almost 5.5 degrees hotter than the average summer month.

Previous reports from the Intergovernmental Panel on Climate Change have raised concerns about the world's progress in meeting the goal set at the Paris Agreement -- limiting warming to 2 degrees Celsius.

An oft-cited report released by a panel of hundreds of scientists last year warned that greenhouse gas emissions needed to be drastically reduced as quickly as possible to limit warming from reaching levels where effects become "irreversible."

The last five years have been the warmest in recorded history, according to NOAA.