Rapid, Anthropogenic Climate Change
Simply stated, within the last generation we have emitted a huge concentration of greenhouse gases into the atmosphere, primarily through the burning of carbon-based fossil fuels. These gases over-insulate our atmosphere, trapping huge amounts of heat that is mostly absorbed by the ever-circulating oceans. The distribution of heat throughout the global oceans is the primary driver of the global climate system, controlling the dominant weather patterns and longer-term cycles like El Niño/La Nina. Even small shifts in the way heat is distributed around the planet can have huge consequences for the weather and longer term climatic patterns we and other life forms experience.
Of course the global climate is always changing so why the big concern? Indeed the Earth has been hotter in the past, with higher atmospheric carbon dioxide levels than we are worried about today, and life persisted without a problem, right? Well yes, but the life forms we know and love on Earth, from polar bears to dolphins to ourselves, evolved in climatic conditions that were MUCH more stable than what scientists are predicting for the next 100 years if we don’t curb our greenhouse gas emissions. The most important thing to understand about climate change is that it is the unprecedented rate at which the system is changing that is the biggest threat to life on Earth. There will be climate winners (i.e. some species will thrive as rainfall patterns shift their way) and there will be climate losers (i.e. refugees from the islands of Kiribati who will have to leave their homeland behind as the rising seas make it uninhabitable), and we need to do everything we can now to mitigate these losses.
Simply stated, within the last generation we have emitted a huge concentration of greenhouse gases into the atmosphere, primarily through the burning of carbon-based fossil fuels. These gases over-insulate our atmosphere, trapping huge amounts of heat that is mostly absorbed by the ever-circulating oceans. The distribution of heat throughout the global oceans is the primary driver of the global climate system, controlling the dominant weather patterns and longer-term cycles like El Niño/La Nina. Even small shifts in the way heat is distributed around the planet can have huge consequences for the weather and longer term climatic patterns we and other life forms experience.
Of course the global climate is always changing so why the big concern? Indeed the Earth has been hotter in the past, with higher atmospheric carbon dioxide levels than we are worried about today, and life persisted without a problem, right? Well yes, but the life forms we know and love on Earth, from polar bears to dolphins to ourselves, evolved in climatic conditions that were MUCH more stable than what scientists are predicting for the next 100 years if we don’t curb our greenhouse gas emissions. The most important thing to understand about climate change is that it is the unprecedented rate at which the system is changing that is the biggest threat to life on Earth. There will be climate winners (i.e. some species will thrive as rainfall patterns shift their way) and there will be climate losers (i.e. refugees from the islands of Kiribati who will have to leave their homeland behind as the rising seas make it uninhabitable), and we need to do everything we can now to mitigate these losses.
Overfishing
To understand the drivers of overfishing one needs to be familiar with the idea of the Tragedy of the Commons. The Commons, as they were called, were the shared fields in which shepherds could allow their sheep to graze. Like the ocean, the Commons had no single owner to say how much grass (or fish) each shepherd could take without there being some left over for the other shepherds. Tragedy ensues because each shepherd has an incentive to use as much of the grass (or fish) as possible before the other shepherds take it- leading to a rapidly depleted resource.
Even though 70% of our planet’s surface is ocean, very little of it is actually owned or protected by any nation or international body. The United Nations Law of the Sea is supposed to regulate what activities can occur beyond nation’s territorial waters (out to 220 miles from shore), but political hold-outs like the United States have never signed-on to this agreement. As a result, most of the ocean is really just a global Commons, ripe for the taking.
It shouldn’t be much of a surprise then most stocks of large, edible fish have been severely depleted from their historic levels. Overfishing has huge impacts for the people who rely on seafood for sustenance (an estimated 3 billion) and on the natural food webs that have been altered by this extraction effort.
To understand the drivers of overfishing one needs to be familiar with the idea of the Tragedy of the Commons. The Commons, as they were called, were the shared fields in which shepherds could allow their sheep to graze. Like the ocean, the Commons had no single owner to say how much grass (or fish) each shepherd could take without there being some left over for the other shepherds. Tragedy ensues because each shepherd has an incentive to use as much of the grass (or fish) as possible before the other shepherds take it- leading to a rapidly depleted resource.
Even though 70% of our planet’s surface is ocean, very little of it is actually owned or protected by any nation or international body. The United Nations Law of the Sea is supposed to regulate what activities can occur beyond nation’s territorial waters (out to 220 miles from shore), but political hold-outs like the United States have never signed-on to this agreement. As a result, most of the ocean is really just a global Commons, ripe for the taking.
It shouldn’t be much of a surprise then most stocks of large, edible fish have been severely depleted from their historic levels. Overfishing has huge impacts for the people who rely on seafood for sustenance (an estimated 3 billion) and on the natural food webs that have been altered by this extraction effort.
Marine Plastic Pollution
The first commercially viable synthetic polymer was called Bakelite, developed in 1907. One hundred years later, plastics have been designed into the very fabric of global human society. Plastics takes hundreds to thousands of years to fully biodegrade. In the meantime they photo-degrade: sunlight makes them brittle and they break up into smaller pieces. A such, every piece of plastic that has ever been produced since Bakelite amazingly still exists as plastic. A majority of that material has flowed down city streets into rivers to the sea, creating a massive plastic soup out of the global oceans.
The effects of plastic pollution on ocean-life are broad and not fully understood. What we do know is that large plastic debris such as rope, plastic bags, and six-pack rings can choke and entangle a huge variety of wildlife. Mother albatross unknowingly feed plastic cigarette lighters to their chicks, blocking their intestines so they starve, and whales can drown when entangled in discarded fishing nets. Beyond these well-documented impacts, less is understood about the hormonal or toxic effects plastic may have when ingested by marine animals. Furthermore, more research is needed to understand if chemical pollutants bonded to marine plastic debris accumulate in the marine food web, the top of which is occupied by human consumers.
The first commercially viable synthetic polymer was called Bakelite, developed in 1907. One hundred years later, plastics have been designed into the very fabric of global human society. Plastics takes hundreds to thousands of years to fully biodegrade. In the meantime they photo-degrade: sunlight makes them brittle and they break up into smaller pieces. A such, every piece of plastic that has ever been produced since Bakelite amazingly still exists as plastic. A majority of that material has flowed down city streets into rivers to the sea, creating a massive plastic soup out of the global oceans.
The effects of plastic pollution on ocean-life are broad and not fully understood. What we do know is that large plastic debris such as rope, plastic bags, and six-pack rings can choke and entangle a huge variety of wildlife. Mother albatross unknowingly feed plastic cigarette lighters to their chicks, blocking their intestines so they starve, and whales can drown when entangled in discarded fishing nets. Beyond these well-documented impacts, less is understood about the hormonal or toxic effects plastic may have when ingested by marine animals. Furthermore, more research is needed to understand if chemical pollutants bonded to marine plastic debris accumulate in the marine food web, the top of which is occupied by human consumers.
