你给的句子有误，不是 climb to，而是不定式 to climb，在句子中用作宾语补足语。请看原文：

Last week, Russia extended an earlier ban on wheat exports. Russia acted after heat, drought and wildfires destroyed about a third of its wheat crop last summer. The ban was placed to make sure Russians have enough wheat. The first ban caused worldwide wheat prices to climb last year by almost fifty percent.

▲ by之后接分数或百分数常用来表示某种“量”的增长或减少的程度。如：

Their pay has been cut by one-third.他们薪水降低了1/3。《柯林斯高阶英汉双解学习词典》

Violent crime has increased by 10 percent since last year.暴力犯罪自去年以来增加了10%。《柯林斯高阶英汉双解学习词典》