Greenhouse gases come in two basic flavors: carbon dioxide from fossil fuels, and emissions from land use — agriculture, forests, peat bogs, and waste management. Fossil fuels are primarily used for energy in three sectors: buildings, industry, and transportation. Transportation is almost entirely oil-based — according to the International Energy Association, about 0.1 percent of transportation energy currently comes from electricity.

Just to make things complicated, people use fossil fuels to make electricity to use in buildings and industry. Well, actually, we use fossil fuels to make electricity — and — we use fossil fuels to make heat to use in buildings and industry. In my previous post, I presented some pretty exciting tables summarizing this global state of affairs (and the accompanying Google workbook). Now, in part 2, a detailed look at building, industry, transportation, and land-use emissions:

Industry: At 28 percent of all GHGs, industry is the single largest source of emissions. However, there is so much variation in manufacturing and construction — and the data is so hard to collect — that an exact allocation is difficult. The relevant part of the IPCC Industry report [p. 460, PDF]:

iron and steel, non-ferrous metals, chemicals, petroleum refining,minerals (cement, lime and glass) and pulp and paper … (ex-petroleum refining) … accounted for 72% of industrial final energy use in 2003. With petroleum refining, the total is about 85%.

Now, when one goes through the rest of the report, it appears that in order to arrive at 85 percent, chemicals must account for over 11 percent of all global GHGs. However, the report advises that no one knows how much the chemical industry emits. But this seems to be the best guess at this point in time.

Concrete is the only industry that seems to produce a major amount of CO2 that does not come from fossil fuels. Steel and aluminum constitute about 4 percent of emissions, but this gives some cause for hope: to produce recycled steel — from scrap — uses only about 40 percent of the energy that making steel from iron requires. And scrap is a bigger and bigger part of global steel production. Recycled aluminum uses only 5 percent of the energy of “virgin” aluminum. In other words, recycling can drastically decrease industrial emissions. The table:

Industry CO2 Emissions
Source CO2 eq Mt % of total
Fertilizer (ammonia) 500 1.02
Ethylene 180 .37
Chlorine 78 .16
Other Chemicals 4,455 9.09
Concrete 1,650 3.37
Petroleum refining 1,508 3.08
Steel 1,550 3.16
Aluminum 526 1.07
Glass, Ceramics 445 .91
Paper 400 .82
Other 2,601 5.31
Total Industry CO2 11,600 28.35

When we add the methane that is needed to process the fossil fuels used for industry, plus some other gases and losses from fuel-use, we get to 13,893 megatonnes of GHGs.

Buildings: We know the general categories of energy-use in residential and commercial buildings, but the percentages of such usages vary considerably around the world, making it very difficult to determine exact breakdowns. In the following table, “Electricity” is used for appliances, some heating, refrigeration, and cooling; heat of all sorts is used for space heating, cooking, and water-heating:

Buildings Emissions
Source CO2 eq Mt % of total
Electricity CO2 7,145 14.58
Heat CO2 4,071 8.31
Cooling nonCO2 1,500 3.06
Heating nonCO2 500 1.02
Total Buildings 11,600 28.35

In order to bring these emissions down, we’ll not only need to use carbon-free electricity — and to do more heating from such electricity — but we will also have to decrease the need for electricity by making buildings better able to retain heat and cold. It will be necessary to try to use as much solar heating and ground-source heat pumps as possible.

Transportation: Somehow, we’ll have to find a way to convert transportation from virtually complete dependence on oil to almost complete dependence on electricity. The figures right now:

Transportation Emissions
Source CO2 eq Mt % of total
Cars, SUVs, light trucks 3,039 6.2
2 wheelers 109 .22
Heavy & medium trucks 1,707 3.49
Air 792 1.62
Shipping 649 1.32
Buses 423 .86
Rail 102 .21
Total Transportation 6,829 13.94

However, just as decreasing industrial emissions should come from decreasing the need for energy, so too transportation emissions should diminish as a result of changing the structure of our living patterns. The denser we can make our residential, commercial, and industrial buildings, and the more we can mix those various functions in a smart way, the less energy required for transportation will be necessary. Plus more walking and biking will replace energy generation. I think that electrified trains will be the most efficient way to move people and freight.

Agriculture: Agricultural greenhouse-gasses are most notable for what they lack: CO2 emissions. Virtually all of the emissions from agriculture come from methane and nitrous oxide because the IPCC assumes that the carbon lost from agriculture is balanced almost exactly by the carbon sequestered in agricultural lands. But what if agricultural regions weren’t being degraded by modern agricultural techniques? According to the IPCC agricultural report [PDF], by 2030, 6,000 megatons of CO2 emissions are preventable provided the soils of the world are built up instead of worn down.

But sticking to methane and nitrous oxide, here is the breakdown for agriculture:

Agriculture Emissions
Source CO2 eq Mt % of total
Excess Nitrogen from fertilizers 2,318 4.37
Methane from livestock belching and gas, CH4 1,952 3.98
Biomass burning 732 1.49
Rice production 671 1.37
Livestock manure 427 .87
Total Agriculture 6,100 12.45

Notice that organic agriculture could pretty easily remove excess nitrogen from fertilizer. But as far as I can tell, there’s no good way to remove methane emissions from livestock belching (and some gas passing), and if livestock were let loose from those horrible factory farms, it
would actually make it harder to collect the manure. So does this mean that a lifestyle change would be necessary? Could we eat much less meat? Or, eat mostly fish? The latter would mean that to solve the problem of too much livestock, we’ll have to protect the oceans. By saving the ocean’s fisheries we could indirectly prevent the worst impacts of climate change.

Forests: The worst effects of livestock and agriculture may actually be their effects on the world’s forests. According to the IPCC, the amount of emissions from forests is the most difficult to estimate. We also don’t know how much can be attributed to livestock, agricultural clearing, or logging for timber. Here is a table of the loss in forests, by area of the world:

Forest carbon loss
Source CO2 carbon stock, 2000-2005 % of total forests
South America -12,833 51.47
Asia -11,000 44.12
Africa -5,134 20.59
Rest of World 4,035 -16.18
Global total of forest loss -24,392 100

Finally, it turns out that waste management contributes almost 3 percent of GHGs — mostly methane from garbage landfills. Again, recycling could eliminate the need for most landfills.

Even without global warming, our energy, transportation, agriculture, and forestry systems are unsustainable. Fossil fuels will eventually become too expensive to use, our agricultural systems destroy the soil, water, and other ecological systems on which they are dependent, and the planet cannot survive without its forests. With the threat of global warming, the need for a revolution of our civilization has never been more necessary.