ok for starters steven harper, the concentration of CO2 (among other greenhouse gases) in the atmosphere. you know, the fact that it is at all time record levels? that would be a "situation". hmm, how can it get worse? with current levels of logging and deforestation due to market demands (a case of the economy ignoring the intrinsic value of natural capital...), we (the earth) will not have nearly enough forest to act as a carbon sink and cleanse the atmosphere if current consumption levels remain static, and population continues to grow. want a source? bill rees, the UBC professor who came up with the idea of the ecological footprint.
bottom line? the climate is changing, and quickly. we have a huge global population and have decimated global fish stocks, we are draining massive aquifers at levels well above their recharge rates, we are consuming non renewable fossil fuels at even faster rates to the point where they will likely become obsolete by the time our grandchildren run the earth (speculation). if we can have effects on this scale in the biosphere, lithosphere, and hydrosphere... then why is it so difficult to admit we can also fuck shit up in the atmosphere in such a short period too?