GetOffYourGas wrote:Sure, we've been polluting since humankind's discovery of fire. But the world population didn't hit 1B until about the time of the industrial revolution (19th century). We are now over 8B. And we're burning a whole lot more per capita to boot. <snip>
A small correction: as of July 1st, the world pop. is estimated to be 7.633B: https://www.google.com/search?q=world+populaiton+2018&rlz=1C1GGRV_enUS817US817&oq=world+populaiton+2018&aqs=chrome..69i57j0l5.5578j0j1&sourceid=chrome&ie=UTF-8
Anyone interested in the details of total and per capita energy use over time both globally and in specific countries should read:
Energy Transitions: Global and National Perspectives, 2nd Edition
by Vaclav Smil: https://www.amazon.com/Energy-Transitions-Global-National-Perspectives/dp/144085324X/ref=pd_lpo_sbs_14_t_2/000-0000000-8675309?_encoding=UTF8&psc=1&refRID=SSWGDMARP0GGVJ4WJG34
Pre-industrial age per capita energy usage (primarily biomass, with some water and a tiny bit of wind) was very low. I don't have the book handy, but the advent of fossil fuels, steam engines and then steam turbines, ICEs, electricity, meatier diets etc. has increased per-capita energy use massively, especially among the wealthiest countries. Some current numbers I remember (in GigaJoules - to convert to kWh divide by (3.6 x 10^6)): EU (as a whole) annual p.c. use 130 GJ; France 155 GJ; Germany 160 GJ; Japan 150 GJ; China (now, owing to their massive industrialization since 1980) 90 GJ; India (just beginning industrialization), 20 GJ. By comparison the incredibly wasteful U.S. has per cap. energy use of 300 GJ. Some of the U.S. difference compared to Germany and France (the two EU states with the most heavy industry) is due to larger size and lower population density (boosts transportation energy) and some due to climate (lots of HVAC use), but much if it is due to housing types (large detached homes in suburban sprawl versus smaller urban townhomes/apts.), and sheer profligacy due to low energy prices (e.g. unneeded SUVs, lack of insulation). U.S. per capita energy use in 2015 was actually 10% lower
than it was in 1970 or 1980, and it's far easier for us to improve our efficiency and reduce our energy usage by a large percentage than it is for countries which are already much more efficient.
It wasn't until sometime in the 1890s that coal overtook biomass as the majority energy source, and not until 1964 that oil overtook coal (but will never reach 50%, as NG and other energy sources have increased). Even so, although the % of the world's energy that comes from biomass has dropped, the total amount
has increased owing to the increase in population, and large numbers of people in poor countries still depend on it for cooking and heating. In India, 300M people still don't have access to electricity. Here's what Smil has to say:
My best estimate of wood consumption (including wood for charcoal) for the year 2000 is about 2.5Gt of air-dry matter (2 Gt of absolutely dry matter, or 35 EJ) and crop residues (about 20% of their total mass) added about 10 EJ for the grand total of 45 EJ or an equivalent of 3 Gt of air-dry wood. For comparison, Yevich and Logan (2003) estimated that 2.06 Gt (about 31 EJ) of traditional biofuels were consumed in in 1985 in low-income countries; Turkenburg et al. (2000) put the end-of-the-century total 45 +- 10 EJ; and Fernandes et al.
(2007) estimated 2.457 Gt of solid biofuels (roughly 37 EJ) in the year 2000, with wood contributing 75% and crop residues 20%, and with households burning 80% of the total and productive activities the rest. Despite major uncertainties all of these numbers cluster around 40 EJ (35-45 EJ, 2.3-3.0 Gt of all solid biofuels) and imply the doubling of wood and crop residue harvests for fuel during the 20th century accompanied by a steady decline of average per capita consumption rates everywhere except in some parts of the sub-Saharan Africa.