Thanks to humanity's addiction to fossil fuels, carbon dioxide levels are the highest they've been in at least 3 million years. For some perspective on this, the last time CO2 levels reached 400 parts per million, the Sahara desert was thick with forests and the Arctic was just as inviting as the Caribbean in terms of temperature. Humans were just a gleam in evolution's eye at that point. We didn't exist during the Pliocene era when sea levels were 80 feet higher than they are now.
Earlier this month, scientists using data taken from devices monitoring the air quality at Mauna Loa, a Hawaiian volcano, confirmed that levels of the heat-trapping gas in the atmosphere passed the much dreaded milestone of 400 ppm. So, what's next now that mankind has gone over Niagara Falls in a metaphorical barrel?
We don't know how bad things are going to get, but we know events related to climate change that we've already experienced -- like Katrina and Sandy -- were calamitous by every standard. With the rapid warming of the oceans and the erosion of ice caps around the world, the environmental impact is expected to be nothing less than disastrous for coastal cities where large populations live. Flooding and severe storms are expected to wreck havoc over large swaths of the planet.
Fish populations, already in decline, will be further decimated, scientists believe, because they won't be able to adapt fast enough to rising temperatures. Deadly algae is expected to bloom in the oceans and choke oxygen-deprived waters even more. No one, including climate change deniers, are predicting that things will get better as the result of increased levels of CO2 in the air.
Still, China and the United States refuse to become partners in the effort to curb carbon dioxide emissions despite being the world's biggest emitters of greenhouse gasses. Neither has taken meaningful steps to scale back fossil fuel consumption because of fears of wrecking their economies. Such recalcitrance has emboldened countries around the world to scale back their commitment, as well.
Maybe one day there will be breakthrough technology that will wean us away from fossil fuels while also reversing the worst effects of climate change. Such a positive outcome is less likely than the worst-case scenario.