The scientific integrity of the California Academy of Sciences’ prominent climate change exhibit has come under attack for two starkly different reasons.

A hearing scheduled today in San Francisco Superior Court’s small-claims department will consider a request by resident Michael Phillips for a $159 refund of his family membership.

Phillips claimed the academy’s climate change exhibit is based on an aging theory by NASA scientist James Hansen and fails to present conflicting evidence.

The landmark theory, which posited that humans affect the climate through carbon dioxide emissions, is roughly 20 years old.

Academy documents show Phillips’ membership dues are being refunded, a decision that spokeswoman Stephanie Stone said will avoid legal costs.

Separately, another exhibit has been criticized by scientist Ken Caldeira, a climate change expert at the Carnegie Institution for Science’s Stanford University-based Department of Global Ecology.

The exhibit promotes cement that Los Gatos-based Calera Corp. said can suck up carbon dioxide.

Caldeira described the exhibit as a “scam” in a string of e-mails to academy officials. The chemical reaction actually requires the addition of expensive alkali and would create waste acid, he said.

Calera Corp. told the academy that part of the process is proprietary, and therefore can’t be published, according to Stone.

Calera officials were not available for comment Monday.