Bill ; We sound like the purveyors of doom , mulling over whether there will be future generations and what state the planet will be in .

Ben ; Yes , but I guess people just need to face facts and accept the evidence we are being confronted with . The bottom line is that it may already be too late to react to what is happening to the planet . Mankind , by dint of his own success and ingenuity , may have sown the seeds of his own destruction . Let us not forget that everything that ever lived , every species , eventually became exinct . Why should homo-sapiens be any different ?
The ice is going to melt . The seas are going to rise . The majority of coastal cities around the world will end up submerged . But incredibly , nobody is preparing for it . I suppose the global warming hysteria has at least been a wake up call .
The real threat to mankind's survival is not melting ice , but rather a lack of energy sources . Oil , coal , gas , all the fossil fuels , will be depleted in another 50 years . If we can capture the energy of the sun , the wind , and the oceans , we will survive not only the coming warm-up but also the cool-down that will follow it . There will be global warming . There will be another ice age following it . That cycle is definite , it has been happening for over 4 billion years on this planet .

Bill ; I guess the only difference is that we will leave a documented record of these changing events on paper and computers and film , instead of just scrawling on cave walls .

Ben ; Don't be so sure about that . There is no way of telling just how bad things will actually get . If mankind survives deep into the future it is conceivable that we may be scrawling on cave walls again .
We should not forget , and this is a fairly contemporary parallel in archaeological terms , that the Neanderthals became extinct because they failed to adapt to a changing world .
I think mankind has reached a very crucial point on his journey . We smugly see ourselves as just one rung below the angels on the ladder of evolution , but in reality we remain merely ' kissing cousins ' with the chimpanzees . I truly believe mankind , at this moment in time , needs to excercise caution .

Bill ; Try expounding that to anyone living in a developed capitalist society where consumerism is the driving force . You would fall flat on your face . The worrying thing is though , they all know it is true but they resolutely choose to remain contemptuously ignorant of the situation .

Ben ; Well , all the evidence is there to be found , it's even in the air we breathe .
Carbon dioxide is accumulating in the atmosphere twice as fast as natural processes can remove it . The concentration of carbon in the atmosphere is now higher than it has been for the last 42,000 years , and quite possibly the last 20,000,000 years . The air we breathe today is vastly different from that breathed by our ancestors throughout the 7,000,000 year evolutionary history of the human race .
So it's not surprising at all that the Earth's climate has once again begun to tilt out of balance . Although this time the natural cycle of heat-up and cool-down has been aided by man's activities .

Bill ; Yes , mankind has become very successful . We swarm over the face of the planet and plunder it's natural resources without a second thought . Perhaps the effects of our activities are now catching up with us .

Ben ; The 1990's were the warmest decade since records began , and are likely to have been the warmest for the last thousand years , quite possibly longer . The top five warmest years ever recorded almost run in sequence . 1998 was the warmest , followed by 2002 , 2001 , 1997 and 1995 . There is no doubt the planet is heating up rapidly , and the rate of warming is actually accelerating .
Climate change predictions have outlined a number of scenarios that range between temperature rises of 1.4 degrees celsius and 5.8 degrees celsius on a global scale over the next century .
The lower end of that spectrum is more than double what we experienced in the twentieth century , the higher end of almost 6 degrees would take the planet into uncharted and extremely dangerous territory .

Bill ; That really is scary . The resulting impacts on mankind and the planet don't bear thinking about .

Ben ; Yes , and what is even more scary is that the resulting impacts are actually predictable . We know what will happen .
The ice caps and glaciers will melt completely , in tandem with accelerating rates of rising sea levels . Hurricanes and typhoons will become much stronger and more frequent , and the intensity of floods and droughts will also increase and become more prolonged . Tropical diseases will spread northwards and southwards towards the poles . Billions of people will lose their water supplies . Complete ecosystems will unravel as plants and animals struggle to adapt to rising temperatures , animals will not be capable of migrating fast enough or far enough to stay within their natural climatic comfort zones . Agriculture will suffer badly , and food supplies will inevitably dwindle .

Bill ; You are painting a very worrying picture , to say the least .

Ben ; Very worrying indeed , but there is more .
These impacts will be disproportionately felt by the poor and the vulnerable in semi-arid and tropical zones , most of whom already live on the edge of survival . Conflict and war over scarce and dwindling resources will become commonplace . There will be wholescale movement of environmental refugees , tens of millions will be made homeless by extreme weather and flooding of low-lying areas .
You need to envision all of this on a global scale of course to even get a glimpse of the devastation that will be caused .

Bill ; I guess that this all depends on mankinds behaviour in the face of the evidence presented to us today and the dreadful consequences of our possible inaction . Do we continue to pump out billions of tonnes of carbon dioxide or do we embark on a transition towards a clean energy economy ?

Ben ; Yes , exactly . There is something else , the acceleration of global warming , once underway , will trigger a series of other dangerous events that are too difficult to quantify .
There are huge quantities of methane locked up in undersea deposits around the globe , more than double the worlds entire fossil fuel reserves . This methane is kept stable by low ocean temperatures and the pressure of water from above . As sea temperatures creep up , large eruptions of this methane will enter the planet's atmosphere . Methane is twenty times more destructive as a greenhouse gas than carbon dioxide . Vast amounts of methane entering our atmosphere will trigger a runaway global warming effect that we would be utterly powerless to halt . It seems very likely that these ' methane burps ' probably triggered past global warming episodes in the Earth's long geological history .
One more thing , the Amazonian rain-forests , often referred to as the lungs of the world will inevitably become drought stricken if temperatures continue to rise . The rain forests will die and release all their locked-up carbon into the atmosphere . This will also add to the global warming scenario and contribute hugely to temperatures rising even further , not to mention spelling doom for the biodiverse ecosystems that the rain-forests support .

Bill ; If things do get that bad , we could be staring extinction in the face . That is the worst case scenario , isn't it ?

Ben ; If we fail to change . If we fail to adapt . We may well go down the same road as the Neanderthals .