Trees, Humans and Climate

Bob Berwyn reports on a study published in Science:

Most trees alive today won't be able to survive in the climate expected in 40 years, [lead author Tim] Brodribb said. The negative impacts of warming and drying are already outpacing the fertilization benefits of increased carbon dioxide.

And a study published by PNAS finds that as many as 3 billion people could face inhospitable temperatures by 2070.

[F]or millennia, human populations have resided in the same narrow part of the climatic envelope available on the globe, characterized by a major mode around 11°C to 15°C [52 F to 59 F] mean annual temperature.

[I]n a business-as-usual climate change scenario, the geographical position of this temperature niche is projected to shift more over the coming 50 [years] than it has moved [in the past 6000 years].

[I]n the absence of migration, one third of the global population is projected to experience a [mean annual temperature] >29°C [84 F] currently found in only 0.8% of the Earth’s land surface.

Update (May 12):  Robert Hunziker points to a study published in Science Advances on dangerous "wet bulb temperture" (TW) conditions. There is an upper limit to the combination of heat and humidity under which humans can survive.

Climate models project the first 35°C TW occurrences by the mid-21st century. However, a comprehensive evaluation of weather station data shows that some coastal subtropical locations have already reported a TW of 35°C and that extreme humid heat overall has more than doubled in frequency since 1979.