However we can rule out the effect of low level clouds causing changes in reflection of sunlight as a cause. (skepticalscience.com)
If low - cloud cover increases as the climate warms, the warming is muted by the additional reflection of sunlight. (climate-dynamics.org)
More ice meant more reflection of sunlight back to outer space, which led to further cooling, which led to more ice, and so on, creating the «snowball Earth.» (ibtimes.com)