While global warming is causing a speedup of many ocean currents, an anomaly is the consequence of Greenland ice melt reaching the Atlantic at the origins of the Gulf Stream current. Reducing salinity, it impacts its driver, namely, the sinking salt water (Science, Feb. 7, 2020, p.612) weakening the current -- its beneficence accounting for the relatively benign winters in Britain and Ireland and extending as far north as Iceland, Norway and southern Sweden
At the same time, an analysis of data from the Argo array, some 4000 floats deployed across the globe to collect data, indicates an acceleration in currents, particularly in the tropics and the Southern Ocean (Science Advances, Feb 5, 2020). Global warming is the likely cause spurring ocean winds to speed currents, although proof awaits more data collection. A speed-up of currents and rising sea levels paints a picture of a rising, raging sea threatening coastal communities (National Geographic, Oct, 15, 2019) that have been popularized by developers in living memory.
The ecosystem is also threatened in other ways, particularly through the demise of pollinator species -- on whom we, too, depend for our necessary crops. A recent paper (Science February 7, 2020, p.626) reports widespread decline in bumble bee populations in North America and Europe. Warming temperature is the likely culprit. A temperature rise beyond the tolerable limits for bumble bees necessitates migration, often to areas that had been too cold for them before but have warmed up now to be tolerable.
Unfortunately, the rate of extirpation has exceeded that of colonization causing widespread decline. The resulting consequences to plant species deprived of the ecosystem services of this pollinator are clearly unfavorable -- if not disastrous -- but have yet to be surveyed.
Meanwhile, wild bee species are in decline worldwide. A halving from an estimated 6700 species in the 1950s to a shocking 3400 in the 2010s was reported in Science News (January 22, 2020). While previous bee studies have addressed declining populations, the evidence collected had been limited to industrially developed Europe and North America. The significance of the new research is its global scope.
In Thailand, for example, the ground nesting bee, Megachili bicolor, is fast losing habitat to expanding urbanization and agriculture.
With
more scientists entering the field, the total number of bees observed
by them has increased as one would expect. But sadly, the number of species
recorded keep plummeting on most continents. The exception has been
Australia where bee species first rose from 300 to 500 in the 2000s.
Then in the 2010s they fell back to 300. What was once seen as a trend
only in advanced countries is now global, and thousands of species have
become either very rare or extinct.
Bees
and other insects like butterflies are vital in that they pollinate 75
percent of our most important crops. Now butterflies are also under
threat. The monarchs in the US are the victims of herbicides like
glyphosate, and global warming upsets their seasonal migration
patterns. They are also losing habitat, the loss estimated at 165 million acres in the US reports the Center for Biological Diversity.
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