Environmental scientists tested a key U.S. river Tuesday for signs of a toxic waste spill from a botched Colorado mine clean-up that prompted a state of emergency in the desert Southwest.

What started as a three-million-gallon (11.4 million liter) orange-hued plume last Wednesday in the swift-moving Animas River dissolved from view as it made its way down the slower San Juan River in New Mexico.

Kenya has pledged to cut its carbon emissions 30% below business-as-usual levels by 2030, ahead of a landmark UN climate summit in Paris later this year.

The East African country is a very small carbon emitter in global rankings, on a par with Singapore and Mongolia, but the move was hailed by campaigners as evidence that developing countries could develop without fossil fuels.

More than a dozen small island nations made an urgent appeal to the UN Security Council for help in combatting climate change, which they said poses a threat to their very existence.

The Council -- more typically a forum for heated debates on the plight of refugees in Syria or efforts to stem the war in Ukraine -- heard pleas from ministers and ambassadors of diminutive nations like Fiji, Samoa and Caribbean countries like St. Vincent and the Grenadines.

The genetic makeup of fish will be crucial in determining whether they will be able to deal with the world’s rapidly warming oceans, researchers have discovered.

Scientists have discovered that certain fish can adjust to higher water temperatures over several generations, but only if they fully utilize aspects of their genetic makeup.

Aiming to jolt the rest of the world to action, President Barack Obama moved ahead Sunday with even tougher greenhouse gas cuts on American power plants, setting up a certain confrontation in the courts with energy producers and Republican-led states.

In finalizing the unprecedented pollution controls, Obama was installing the core of his ambitious and controversial plan to drastically reduce overall U.S. emissions, as he works to secure a legacy on fighting global warming. Yet it will be up to Obama's successor to implement his plan, which reverberated across the 2016 presidential campaign trail.

Only aggressive efforts to rein in global warming coupled with a rethinking of the British countryside will save many native species of butterfly, according to a study published Monday.

"Widespread, drought-sensitive butterfly population extinction could occur as early as 2050," scientists reported in the journal Nature Climate Change.

A plume of orange muck from a large mine waste spill in Colorado has drifted about 55 miles (90 kilometers) downriver and is closing in on New Mexico, prompting communities to take precautions until the sludge passes.

New Mexico Environment Department spokeswoman Susan Majure said Friday that the contaminated water is about (10 kilometers) 6 miles from the state line.

A recent study led by Georgina Mace, ecosystem professor at University College London, indicated that governments across the world have failed to grasp the risk that population booms in coastal cities pose as climate change continues to cause rises in sea levels and extreme weather events. Mace is director of the UCL Centre for Biodiversity and Environment Research.

Mace says population growth in coastal areas can lead to big increases in exposure to extreme weather. The biggest direct effect of projected climate change is heat waves. The number of people dying from extreme heat could increase twelvefold by the end of this century, as a result of global warming combined with increasing numbers living in affected areas.

The discovery of a genetically distinct group of eastern grey kangaroos sheds light on how they survived aeons of climate-induced expansion and contraction of their grassland habitat, say researchers.

The population, unique to the Sunshine Coast in Queensland, formed as a result of a larger population becoming fragmented due to climate-induced changes in vegetation, they report in a recent issue of PLOS ONE.

The balance of various plankton species will radically change as the world’s oceans increase in acidity over the next 85 years, according to a new study released this week.

By 2100, ocean acidification will have grown to such an extent that some species of phytoplankton “will die out, while others will flourish,” according to a report by the Massachusetts Institute of Technology, where experts teamed up with the University of Alabama to conduct the study.