Effect of humans on the environment

How come it seems that possible change in agriculture output is never mentioned by most people in global warming debates, am I missing something?

Rajendra Pachauri, who chairs the Intergovernmental Panel on Climate Change (IPCC), will make the call at a speech in London on Monday evening.

UN figures suggest that meat production puts more greenhouse gases into the atmosphere than transport.

Humans are perhaps the most successful species in the history of life on Earth. From a few thousand individuals some 200 000 years ago, we passed 1 billion around 1800 and 6 billion in 1999. Our levels of consumption and the scope of our technologies have grown in parallel with, and in some ways outpaced, our numbers. [Add]

But our success is showing signs of overreaching itself, of threatening the key resources on which we depend. Today our impact on the planet has reached a truly massive scale. In many fields our ecological "footprint" outweighs the impact of all other living species combined.[Add]

We have transformed approximately half the land on Earth for our own uses -- around 11 percent each for farming and forestry, and 26 percent for pasture, with at least another 2 to 3 percent for housing, industry, services and transport [1]. The area used for growing crops has increased by almost six times since 1700, mainly at the expense of forest and woodland [2].[Add]

Of the easily accessible freshwater we already use more than half. We have regulated the flow of around two thirds of all rivers on Earth, creating artificial lakes and altering the ecology of existing lakes and estuaries [3].[Add]

The oceans make up seven tenths of the planet's surface, and we use only an estimated 8 percent of their total primary productivity. Yet we have fished up to the limits or beyond of two thirds of marine fisheries and altered the ecology of a vast range of marine species. During this century we have destroyed perhaps half of all coastal mangrove forests and irrevocably degraded 10 percent of coral reefs.[Add]

Through fossil-fuel burning and fertilizer application we have altered the natural cycles of carbon and nitrogen. The amount of nitrogen entering the cycle has more than doubled over the last century, and we now contribute 50 percent more to the nitrogen cycle than all natural sources combined. The excess is leading to the impoverishment of forest soils and forest death, and at sea to the development of toxic algal blooms and expanding "dead" zones devoid of oxygen.

In mid- to high-latitude regions, moderate warming benefits
crop and pasture yields, but even slight warming decreases
yields in seasonally dry and low-latitude regions (medium
confidence).

Modelling results for a range of sites find that, in mid- to highlatitude
regions, moderate to medium local increases in
temperature (1-3ºC), along with associated carbon dioxide
(CO2) increase and rainfall changes, can have small beneficial
impacts on crop yields. In low-latitude regions, even moderate
temperature increases (1-2°C) are likely to have negative yield
impacts for major cereals. Further warming has increasingly
negative impacts in all regions (medium to low confidence)
[Figure 5.2]. These results, on the whole, project the potential
for global food production to increase with increases in local
average temperature over a range of 1 to 3ºC, but above this
range to decrease

Worst Environmental Problem? Overpopulation, Faculty Says

Overpopulation is the world's top environmental issue, followed closely by climate change and the need to develop renewable energy resources to replace fossil fuels, according to a survey of the faculty at the SUNY College of Environmental Science and Forestry (ESF).

Increasing food production to feed an increased population results in yet another increase in population.

From the book Ishmael

The Royal Society and the National Academy of Sciences on Population Growth and Sustainability

World population is growing at the unprecedented rate of almost 100 million people every year, and human activities are producing major changes in the global environment. If current predictions of population growth prove accurate and patterns of human activity on the planet remain unchanged. science and technology may not be able to prevent either irreversible degradation of the environment or continued poverty
for much of the world.

The following joint statement, prepared by the Officers of the Royal Society of London and the United States National Academy of Sciences, reflects the judgement of a group of scientists knowledgeable about the historic contributions of science and technology to economic growth and environmental protection. It also reflects the shared view that sustainable development implies a future in which life is improved worldwide through economic development, where local environments and the biosphere are protected, and science is mobilized to create new opportunities for human progress.

Through this statement, the two academies wish to draw attention to these issues and to stimulate debate among scientists. decision makers. and the public. In addition. the two institutions, in cooperation with other academies, propose to organize a scientific conference in early 1993 to explore these issues in detail.

THE REALITY OF THE PROBLEM

Scientific and technological innovations, such as in agriculture, have been able to overcome many pessimistic predictions about resource constraints affecting human welfare. Never. the less, the present patterns of human activity accentuated by population growth should make
even those most optimistic about future scientific progress pause and reconsider the wisdom of ignoring these threats to our planet.

Unrestrained resource consumption for energy production and other uses, especially if the developing world strives to achieve living standards based on the same levels of consumption as the developed world, could lead to catastrophic outcomes for the global environment.

In places where resources are administered effectively, population growth does not inevitably imply deterioration in the quality of the environment. Nevertheless, each additional human being requires natural resources for sustenance, each produces by-products that become part of the ecosystem, and each pursues economic and other activities that affect the natural world. While the impact of population growth varies from place to place and from one environmental domain to another, the overall pace of environmental changes has unquestionably been accelerated by the recent expansion of the human population.

http://dieoff.org/page7.htm

http://www.population-security.org/mumf-94-03.htm
circa 1969
The Rockefeller Commission Report and the NSSM 200 response are arguably the most important documents on overpopulation ever written. Our country and the world would be very different today if the recommendations in these documents had been implemented.

a world doomed by its passive acquiescence to and over-dependence on its own overdone technologies

According to a recent poll of SUNY professors, overpopulation is the #1 environmental concern. So I am surprised that politicians and the press haven't made this an issue, especially after the UN came out with such an urgent warning of the consequences of overpopulation on the environment. But more on that to come.

http://www.newswise.com/articles/view/551353

Researchers at the Netherlands' Eindhoven University of Technology have, for the first time, successfully produced laboratory-grown steaks. The process, though complex, involves animal myoblasts (basically, stem cells for muscles) – noninvasively extracted from adult livestock.

Then, when cultivated in a nutrient medium that includes products derived from unborn bovine fetuses – obviously, very invasively extracted – these cells are capable of rapidly dividing to form new muscle tissue...

Overpopulation where it is most prevalent (ie. in developing/third world nations) has a very limited impact on the enviroment - it is these 5 billion people who are effectively subsidising our extravagent, totally unsustainable lifestyles in the West.

A huge chunk of the global populations can't afford meat, don't have access to electricity, don't drive cars, etc.

And our population is, as OmCheeto points out, pretty much constant (if not in decline).