this question has been asked hundreds of ntimes ,check all the questions on global warming ,hundres of opinions ready ,it was even a featured question with over 6000 answers by Al Gore .
but you asked for it so here is my opinion
global warming is one of the Mega threats that loom over humanity,with many related factors each as mega as the other
in North Africa,India,Mexico ,millions of people are effected by land loss and desertification
In the days of the dinosaurs this planet was under an aquiferus manta ,a mist that covered the entire earth ,and there were no desserts .
Count how many there are today,and all of them are as a result of mans actions.
the sahara used to be forrests,it is now a dessert that grows by 7kilometres per year
arabia ,irak ,iran used to be fertile lands in biblical times
Ghengas Kahn put every thing to the sword and torch turning vast territories into desserts,and to make sure he filled all the wells with sand.
in recent times thousands of people have died because of exessive heat,usually old people.in India ,Mexico and France,
Deforestation causing desertification,the desert conditions causing very cold nights and scorching hot days
in china, thousands of what used to be farmers are running for their lives from the dust storms that have burried about 900 of their towns,and villages, transforming their lands into dessert,
and instead of producing food they are now needing it from some where else,
the Chinese will drastically effect the world food prices when they start buying water in the form of grains(1 ton of corn represents 1000 tons of water) ,at any cost destabalising governments, in some countries ,could be the result
(are you seeing more Chinese around interested in buying agricultural lands??? ,we do here in Mexico)
so as far as the food production is concerned Global warming or some of its effects are serious,
each degree rise in temperature means 10%crop loss
more landloss because of desertification every year,we have less areble land to produce food ,for an extra 70 million people ,and there is less and less water (because of deforestation),they are overpumping deep carbon aquifiers to irrigate this production ,
and plowing more and more unstable lands ,because they have lost so many million hectares to desertification ,
because of bad farming practises ,such as using fertilizers and heavy machinary or over grazing.
(Ghengas would have been envious of the effects of modern Agriculture)
and there are less and less farmers to do it..because so many of their sons are leaving for the cities
Our consumption of water is ever increasing and our drinkable water supply is shrinking because of polution ,and the production of potable water is less all the time because of deforestation.
we are living in a bubble economy and when the bubble bursts
food prices will sky rocket,and so will the price of water.
the wars of the future will be for water and we will be up to our ears in the wrong water
RISING SEAS result in more landloss
The northpole is melting ,and we will know it without ice in our life times.
this does not affect the sea level because it is ice that is already in the water.but the melting ice from Green land and the south pole ,are another matter.
Global warming is in theory reversable,but it will mean global co operation between all countries ,and taking into account human nature and the world politics ,it is unlikely that this will happen,
At least not untill we are all in the middle of planetary disastres and it becomes a battle for the survival of humanity every where.
However
Almost all governments in the first world and many others who deal with them,are already working on this for a long time ,
In Mexico many farmers are being persuaded Agro forestall farming which includes trees ,like shade grown coffee
and many countries like Germany and the USA ,for example have made heavy commitments to reduce carbon emissions
Countries like Australia ,Denmark,USA and South Africa to name but a few are spending a lot on alternative energies ,
but all of this is still far to slow
greed to further exploit the petrolium business prevents fast positive advancement
SOLUTIONS
if you want to help the planet ,plant a tree every week ,if EVERYONE on the planet did this, we would be able to reverse the destructive processes,and start creating more biomass again.
reduce carbon emisions,and they are already working on that by alternative forms of energy and regulations on carbon producing materials,aerosol cans,burning rubbish,industrial chimneys,powerplants etc.
the world bank pays large subsidies for reforrestation to capture carbon and the best tree for this is the Pawlonia
Waterharvesting projects ,such as millions of small dams.to redirect over ground waterflows from the rains into the ground to supply subteranian water supplies.
the protection of existing forrests.and the production of water
stop building more highways,urban planning to include vegetation stop building cities encourage people to return to the land to conduct their business from there which now has become possible thanks to the internet.
education to motivate people to auto sufficiency by building more home food gardens.
education on environmental awareness
education on family planning to curb over´population
Agricultural education and improvements to follow the principals or sustainability and soil management.
more land design to prevent bush fires,such as--fire breaks
regulations and control for public behaviour
alternative effeciant public transport to discourage the use of the internal conbustion engine
recicling wastes,limit water use
i am a Permaculture Consultant for the department of Ecology for the regional government in Guerrero Mexico