shortest cycle is the solar cycle of 11 years or so. plus it has a longer cycle and we are hitting rock bottom on that one by 2020 or so (grand miniimum). we do have longer data though from ice core drilling in greenland and antarctic and stuff.
also animals are not likely to adapt the change if it happens so quickly. we heading to mass extinction here if we increase temperature too fast. plus the more of the ice mets the faster the temperature actually increases. after 1.5 degrees increase we will find it impossible to reverse the change. also means more refugees since a lot of africa asia and south america will be inhospitable. starving because of less farmable land and more people in one place. climate change means also more disasters, more droughts and more floods.