While your question isn't ideal, in that it's 3 separate questions and there's not much indication that you've done any research, I'll answer anyway.
Is year twenty -thirty an accurate prediction for polar ice
Nobody knows if it's accurate. It's certainly a reasonable estimate based on current rates of decline and continued warming. Predicting something like that with accuracy, however, is impossible. But they can usually make pretty good estimates with careful study.
Also, I wouldn't call it an extinction of ice because the ice will return every winter, it's just an ice-free summer. Is it still bad? Yes. An ice-free Arctic in summer should be prevented if we can.
A.) Is there a model to show just how much our forests absorbs green
This is also a very difficult question. Forests absorb CO2 but they also release it when plants and animals die and/or get eaten.
NASA estimates up to 30% of our CO2 is currently absorbed by all the forests in the world, but the article describes the difficulty in reaching that estimate. Similar estimate from this article.
The problem, of-course, is we can't exactly double or triple the amounts of forests we have in the world. We don't have that much free space. Maintaining forests and planting trees can help with climate change but it's unlikely to ever be a fix.
Will an abundance of CO2 & methane-gas over load the earths forests &
oceans natural ability absorb such gases and start to kill them off.
No. Methane is too scarce to have much effect and CO2 is, if anything, good for plants, not bad for them. Some studies suggest increased levels in CO2 increase plant growth. There are other related problems. Flooding, hurricanes, droughts, salt from storm surges can hurt, not help plant growth. While the CO2 increase can be a boost to plants, environmental changes can hurt. CO2 isn't a pollutant and it doesn't kill planets at high levels. Greenhouses, for example often store 3 or 4 times the normal CO2 concentration without any harm to the plants.
C.) Does our ocean's plankton act as a mechanism to recycle the atmospheres CO2 Green house gases.
Not as well as forests. Plankton does absorb a lot of carbon by photosynthesis but most gets returned back into the atmosphere.
Although a small but possibly significant percentage of the sinking
organic material becomes buried in the ocean sediment, most of the
dissolved carbon dioxide is eventually returned to the surface via
ocean currents - but this can take centuries or millennia.
It's also unclear how much longer the oceans will continue to absorb carbon or if they will start to release it as they warm up.
It's better to ask one question at a time, not three or four, and also, do research before you ask.