Jean Jouzel

A vast system of Atlantic currents that delivers warmth to northern Europe is at risk of collapse, according to a growing body of research. The latest study to warn of its demise finds there is at least a 10 percent chance that a collapse may already be “locked in.”

In the icy waters of the Southern Ocean, whales and other marine mammals rely on krill to survive. But as the market for human dietary supplements and animal feeds booms, and climate change reduces krill populations, scientists worry there may not be enough to go around.

With warming set to pass the critical 1.5-degree limit, scientists are warning that the world is on course to trigger tipping points that would lead to cascading consequences — from the melting of ice sheets to the death of the Amazon rainforest — that could not be reversed.

Backed by the UN, an alliance of conservationists and policymakers is devising new ways to finance the preservation of biodiversity by placing economic values on ecosystems. Some analysts say such schemes have the potential to boost conservation, but others are skeptical.

Despite decades of studies and climate summits, greenhouse gas emissions continue to soar. Energy scientist Vaclav Smil says it’s time to stop ricocheting between apocalyptic forecasts and rosy models of rapid CO2 cuts and focus on the difficult task of remaking our energy system.

Nature-based initiatives, such as planting mangroves and revitalizing wetlands, have proven effective in making communities more resilient to climate change. But international funding has shortchanged such solutions in favor of more costly and less efficient engineering projects.