Our ecological crises: Wake up and smell the stats
• Humans now affect over 80% of the world's land, 100% of the oceans and 100% of the atmosphere. Around 40% of the oceans have been "strongly affected" by our activities.Note that none of these are projections of present trends, they all relate simply to our present condition. This is currently an unsystematic sample; I have not (yet) tried to cover all of the various ecological and resource crises. This post may grow as I continue to gather more information.
• Half of the world’s tropical forests have disappeared since World War II and roughly another 10 million hectares are being felled each year — the equivalent of 40 football fields every minute. The majority are being cleared by illegal loggers.
• Seventy-seven percent of global fisheries are fully exploited, over exploited or have been depleted. Based on 1998 data, the UN Food and Agriculture Organization estimates that global fishing fleets "are 2.5 times larger than needed."
• Marine apex predator numbers (i.e. large fish and sharks) have declined by 90% over the last 50-100 years, mainly due to overfishing (more stats on marine life decline). Another recent study put tuna decline at 60% in the last 50 years.
• Deep-sea trawling damages an area of sea bed twice the size of the contiguous USA each year.
• We're removing 9-10,000 tonnes of fish from the ocean every hour.
• As far as we can work out (and there are wide error margins on this one), species are currently going extinct at something like 100-1000 times the background rate of extinction, faster than at any time since the extinction of the dinosaurs 65 million years ago. It is likely that somewhere between 5,000 and 30,000 species become extinct each year. All the primary drivers of these trends are linked to human activities: land use changes, habitat destruction, pollutants, invasive species, anthropogenic climate change.
• Twenty-two percent of the world's plant species are threatened, and another 33% have an unknown status.
• Twenty-two species of Australian mammals become extinct between 1900 and 1960. Recently, mammal populations in Kakadu have gone into freefall.
• In the 1950s there were 450,000 lions worldwide and now there are only 20,000. Leopards are down from 700,000 to 50,000, cheetahs from 45,000 to 12,000 and tigers from 50,000 to just 3,000. And in the last forty years, elephant numbers have halved across protected areas in West and Central Africa. Globally, since 1970, wild vertebrate numbers have declined by almost one third.
• One study in 2001 put the annual cost of alien invasive species to the global economy at US$1.4 trillion annually, or about 5% of total GDP.
• Overall, current ecological damage is estimated to cost the global economy US$6.6 trillion annually (yes, with a "t").
• An area of arable land roughly the size of Greece or Nepal is lost to soil erosion and desertification each year. Since 1950, 1.9 billion hectares (4.7 billion acres) of land around the world has become degraded.
• By 1995, humans consumed 20% of global net terrestrial primary production. By 2005, it was 25%.
• Earth overshoot day occurs earlier each year. This is a notional measure designating the point in the year where global consumption exceeds the annual renewable biocapacity of the planet. In 2011, it falls on 27th September. Another way of saying this is that in 2010 the worldwide human population used about 135% of the resources the earth can generate in a year.
• Between 2000 and 2010, the number of cars and motorcycles in China increased twentyfold and there are now between 800 million and one billion cars in the world.
• As we burn 196,442 kilos of coal, 103,881,279 litres of natural gas and 150,179 litres of oil a second, we're dumping 62,500 tonnes of heat-trapping emissions into the earth's atmosphere every minute. Since the industrial revolution, we have increased the carbon dioxide in the atmosphere by more than 40% and increased the acidity of the oceans by 30% (a rate faster than anything seen before in Earth's history). The radiative forcing of the carbon dioxide human activities have put in the atmosphere is the equivalent of adding the energy of more than ten Hiroshima bombs every second and is likely the most significant contributing factor in Greenland losing around 9000 tonnes of ice every second (and accelerating), in about 90% of glaciers globally retreating, in precipitating the largest marine migration in two million years due to warming oceans and in ensuring that the last 318 consecutive months have had a global temperature above the 20th century average. The last month with below average temperatures was February 1985.
• Arctic summer sea ice has declined by 40% in extent and more than 75% in volume over the last three decades and 2011 saw new records for lowest extent and volume since records began. Due to increased summer melt, the fabled North West passage through the remote islands of Canada has been open to commercial shipping without icebreakers only four times in recorded history: 2011, 2010, 2008, 2007.
• Nearly 5.5 billion people (about 80% of global human population) live in an area where rivers are seriously threatened.
• The rate at which we are extracting groundwater has more than doubled between 1960 and 2000 and since 1960 18 trillion tonnes of water have been removed from underground aquifers without being replaced, enough to raise global sea levels by an average of 5 cm.
• In 1960, the Aral Sea was the world's fourth largest lake yet by 2000 it had shrunk to 20% of its original size due to over-irrigation on its feeder rivers.
• We put more than six million tonnes of plastic in the oceans annually, which is something like eight million pieces of litter each day, and over 119,000 items floating on every square kilometre of ocean.
• It is likely humanity has had a greater effect on the nitrogen cycle than any other phenomenon for the last 2.5 billion years.
I also posted some further statistics back here, though have not had a chance to post links to all the sources of those, and their credibility is something of a mixed bag.
Posts
